Potty training a very stubborn 2/5 year old girl

Loredana

Hi everyone, we started really potty training her on Monday. She has fone potty 3 times for pee. The issue is that she holds it for so long that it ended up hurting her, but she wont let the pee go, not even on a diaper. Her diapers are dry, she really wants to use the potty but screams due to I'm guessing how much pee she is holding, we brought her to the doctor as daycare told us that may be a uti, but doctor said there is no signs of uti, is just her holding the pee for longer than her bladder can handle, but again, she wont go not even on the diaper, she keep telling us she needs to go potty. When the pee try to comes out she freaks and screams and cries, when the pee actually comes out, we congratulate her to motivate her and to make sure she understand that after releasing the pee it feels good, so to not hold it, but is not working. Tonight she woke up screaming at 1 am because wanted to go potty (she had a pullup on)it took us good 40 min in the washroom until she couldn't hold it anymore to release the pee. We are in a really need of Some advice please? !!!