L.C.
Hi I.,
If she is taking a multiple vitamin then she is getting all the vitamins and minerals she needs. Don't worry so much about eating too much of one kind of food or trying to balance her diet. Kids that age are usually picky. Some will only eat French Fries. My niece would only eat chocolate. It sounds like your daughter eats pretty healthy foods - milk, cheese,yogurt, peanut butter - all good sources of protein. If she wants to eat peanut butter all day let her - it won't hurt her as long as she's getting her milk also. Does she eat any fruit or veggies or eggs or chicken? Just keep trying new things every day. She will eventually start eating new foods but until then I would let her eat what she likes. Does she ever want to eat what her older sisters are eating? That might be a way to get her to try some new things. Some babies are naturally smaller. I wouldn't stress about it unless the doctor says that there is a reason to be concerned.
Good luck! I hope this helps.