Even though girls learn sooner than boys, I don't think I would be tearing my hair about it if she is only 2 1/2. The worst thing you can do is push it when the child doesn't want to learn it. Try putting her back into diapers or pullups and giving the entire topic a rest for a month, without mentioning it at all. In the meantime, get one of the good books on potty training from the library or bookstore and read it. They are full of good ideas.
Bring hee in every two hours give her a book let her hang out. Being 2 1/2 this ia the perfect time to start but it may take awhile. Does she hide when she goes in a diaper? That's a good sign she is ready. When she hides bring her to the toilet and let her sit for awhile. I used stickers for both my kids when they went they got a sticker. I brought them w me when I bought them. Imagine buying your child something they can't have unless they go. My kids tried to go the second we got back from the store so they could have one. Good luck and be patient!