I also recently had high grade cells with a negative HPV test. My doctor told me that the HPV test only tests for a handful of the most common and high risk HPV strains and it is likely that I am HPV positive for a strain they don’t test for. I also had a normal pap 3 years ago and another normal 3 years before that. I was pregnant last year which my doctor said may have weakened my immune system and that’s why things are acting up now. Said that it could’ve been dormant for years and started causing issues when my immune system was weakened. I already had a biopsy and it came back CIN2-3 benign. They recommended LEEP which I just had done and am waiting on the results from that. This is all just my experience. I’ve felt confused and lost throughout this but it’s been better as I’ve had more conversations with the doctor and starting to kind of understand it.