Diaper sizing question

I need help. My 3 month old weighs almost 15 lbs and has quite chunky thighs and belly. (I think it’s adorable though lol) her size one diapers were pretty easy to tell I needed to size up because they were getting harder to put on and like there would be a gap on the sides that would show her skin... well her size 2 diapers are starting to do that now... is it really possible she could be in size 3 already? I mean I put one on her tonight just to try it and it fit way easier than the 2’s.... I just don’t know what I’m doing lol here are pictures of her in a size 3....