Mom is being overly permissive for whatever reason, competition to be the fave parent, laziness, ignorance or whatever.  She isnt listening to your valid concerns.  I doubt that anything you or we say is going to make much difference.

If I were you, I would give serious thought to how this relationship is going to go.  Read around on this site and you will see many step-parents having to live with intolerable situations because the bio parent isn't doing their job.  If you want to stay in the relationship, it might be best to live separately and just date.

If you are considering marriage, just face the probable reality of living with the girl.  Also consider your GF as the mother of your children.  Is that how you want them parented?

Remember, when people show you how they are, believe them.  Good luck.

Yes, the makeup is too young. Not teaching her to ride a bike or swim is, IMO, lazy on your GF's part. Those are up there with dressing herself and other hygiene, learning to tie her shoes, cut her food, and other things a parent should teach. Something tells me she lets the daughter sleep in her bed and play an ipad all day, too. The fact that she dismisses your input for being "not a parent" is the worst, though. Like your girlfriend is so much wiser than you simply because she got pregnant. Think long and hard about making any kind of commitment with her and by all means, do not get her pregnant.

ETA the above is the strange combination of spoiling and neglect that i have read about over and over here and seems to be common in *dysfunctional* divorce/coparenting situations, along with poor boundaries with the ex. 

Your GF sounds like a terrible parent. Permissive and child-centric. You will always come second and obviously the kid can "do no wrong". Also, she seems VERY dismissive of you calling you "not a parent". While this is a true fact, I'd have a problem with someone not listening and valuing my opinion. So disrespectful. Unless you like wearing a bullseye on your back, get out now. 

I have 2 SDs, ages 5 and 8. They both wear makeup when they're playing dress up. They do not wear it outside of the house. Both can ride a bike and swim.

It sounds like your GF is a permissive parent who coddles her kids. That may not end well for you.

For the food issue it depends. I didn't fight with my son when he was younger about food but that was because he was so underweight that getting him to eat anything was important.

I definitely am against the make up at age 7. If she was just playing dress up that's fine. But encouraging it on a regular basis sends her the wrong message at a very young age. This is the time a young girls life where they are molded before they hot Thier teen years. Getting her involved in activities that either inspire her creativity, takents or athletic ability should be the focus. Not teaching her that her looks are a priority. 

Self esteem is built from within not from the acceptance of others 

OP, she is telling you loud and clear to butt out of her parenting and mind your own business. Even if we all agree with you, she is still going parent as she sees fit. She's raising a child who will be very dependent, lacking in self-confidence, entitled, and unlikely to be a functional adult. But she's right - she can raise her kid however she sees fit.

All you can do is decide whether or not you want to stick around for the show. Because if you start demanding that she eat differently and learn to ride a bike, you will be mean stepdad in no time. So decide if you can accept this situation AS IS, or not.

I agree with tog regarding the solution to this situation: butt out or get out.

However, if you'd like opinions on behaviors:

When you say she wears make up, are you talking some lip gloss and blush, or a full face with fake lashes and contouring? I started wearing make up in middle school, but before that, my mom would sometimes let me wear tinted lip gloss, some VERY muted eyeshadow, and some blush. I think I wore it to a wedding, some Girl Scout awards, and for some pictures. I also had play make up, and sometimes I would go with my mom to the store or something with it on. I don't find it weird unless she is using high-end, full coverage stuff or talks about being ugly without it. 

The food thing is also a non-issue for me PROVIDED that mom tries to get her to eat other things or makes her try new foods. YSS was (still is) a pain when it came to food. We always made him try the food on his plate, but didn't make him keep eating it. He's not a big fan of meat unless it's ground (texture issue; he'll eat any ground meat I put in front of him). He doesn't like cooked veggies, but will eat them raw. Same with fruit. He cant handle any spice. 

I've learned with YSS to make what I'm going to make, ensure at least one thing I make is something I know he'll eat, and then tell him to get a fruit or veggie from the fridge. I've also tried to make foods healthier - use wheat breads and pastas, sauces and spreads with less sugar, ground turkey instead of ground beef, etc. PB&J isn't the worst food for a kid to eat. Actually, none of what you mentioned is.

Having said that, what it DOES sound like is your GF may not be interested in TEACHING SD anything new, whether that be skills (bike riding, swimming) or foods. Part of parenting is making kids push their boundaries to try new things. Not doing that is doing a disservice to SD. BUT, I'm also not going to assume that her not being able to swim or ride a bike well = GF neglecting SD. If SD is a stubborn child, your GF may have a routine she uses to ease SD into things that works for her, even if SD is a little more behind than you think is appropriate.

Basically, none of this makes me think that GF is neglecting SD. She COULD be, but there are also plausible explanations as to why SD struggles. But, I reiterate that if you don't like it, you can end this relationship because your GF has made it clear she doesn't want your input.

6 is too young other than for a dress up play session.

IMHO of course.

Playing dress up for a girl OK but not out of the house., I think of dress up make up as lipstick. Learning to swim a necessity for safety so you don't drown,  God forbid ! And learning to ride a bike? Depends on where you live. If you're in the city maybe it isn't safe but you can learn somewhere. My GKs had bikes with training wheels at four and can ride fine now it's six. They live in a village where there are sidewalks but where I live there are none and semis go by on the road.  (One neighbor son was killed by a car, hitting him on our road when it was dusk about 30 years ago. I was never forget the primal scream from his mother. ) It basically is not a safe road for kids to ride on - but there is a bike path up the road on the bed of old railroad tracks. It doesn't mean you don't learn to ride the bike. Even if they eat odd food or limited food unless it's going to hurt them? There isn't much you can do - some kids just are totally picky. I have one grandson who eats the way this girl does, and the other one eats every vegetable and fruit under the sun;  they are brothers, so they're getting the same food offered to them.

If your girlfriend is adamant about not pressuring the kids on anything? You will have problems if she is flexible and you can talk her into letting the kid learn to swim and ride a bike? Then it might work out. The food is another thing slash some kids are just picky eaters.