Nothing is working!!!! I need HELP!!!

My daughter turned 3 in March and we keep going back and forth with potty training!!! She just won't do it!!! I've tried everything! Went out let her pick out her panties, bought her her own potty chair, I've done a potty chart where she gets to put on stickers every time she goes and win prizes, that was going good for awhile but then she lost interest , so I tried just keeping her in panties and taking her to potty every 30 min that was working but not anymore. Even the daycare has been helping taking her to the potty rewarding her and so on..... I'm out of ideas and I'm sooooo frustrated I just don't know what to do any help would be great!!!!! P.s. She is my third child her two older brothers were so easy to potty train just put them in underwear and they were good no accidents or anything!!!