Baby just wants to be standing???

My daughter is 15 weeks and all she wants to do is be standing ( with my help obviously) I try and sit her down and she doesnt let me bend her legs she will push to keep them straight. Even when I just want to carry her she wants to be upright. I sit her down and she will try with all her might to get up. I feel like it's bad her forcing herself that much and putting weight on her legs so soon my mother in law says it can make her legs crooked. Anyone else's baby do the same?