Potty training

My daughter Dakota is 20 months old, she is very independent and stubborn as ever. It's come time to start potty training, I have bought the potty and she will sit on it for a minute or two, then thats it. She doesn't want anything to do with it after that! I don't want to push her into this but I don't want her to get to old and way to stubborn. They say that you shouldn't wait to long to start your child. Well its been 2 months of sitting on the potty, and no results! I don't know what to try next, I'm at a loss for words.I have tried to reward her for sitting on the potty, but its not working anymore. I hope that she is not going to fall behind with other kids her age. I want to her learn how to use the big girl potty. I have also tried to use regular underwear, so when she pees she become wet and uncomfortable, but it doesn't seem to bother her. I need some advise! Please!!!