Breastfeeding issues :(

Hi. So, my daughter is 15 weeks old. She’s always been good at nursing and gained weight well for the first two months but now for the past two weeks or so, she will only nurse for about 5 minutes at a time and refuses to latch back on after that. I’m lucky if I can get her to eat five minutes every two hours. I weighed her before and after an 8 minute feed, thinking maybe she was just getting super efficient, but she only drank 2oz in that time :(. My supply seems fine, I still have leftover milk after she eats and am able to store about six extra ounces each day to freeze by pumping once...but she will not empty my boobs. We’ve also taken her to the doctor when this first started and they checked her for ear infections, heart/lung issues, congestion, etc and said she was fine. I was thinking maybe it’s reflux because she has battled that since day one BUT tonight we tried to offer her more breastmilk from a bottle after she was done nursing and she drank another 2 oz. so it’s not the eating itself that she won’t do, (which I feel like she would reject if she has bad heartburn) but my breasts that she seems to have a problem with. When we do feed her from a bottle, we use a slow flow nipple (tommee tippee) and do paced feeding so I don’t think it’s a flow issue either. I’ve tried all the different nursing positions too but she still finds some way to turn away from my breast and fuss u til I stop trying to get her to latch again. Idk what to do, and I’m so sad that she doesn’t want to eat from me so much anymore and worried that her weight gain has slowed down. Does anyone have any suggestions or similar experiences?

Side note: idk if this is relevant or not, but she has had a low grade fever off and on for a couple days also. We told her doctor and they checked her when she came in but when they checked her it was gone??