period missing for almost 2 months, partner had a vasectomy?

Around 4-5 days ago I started getting some random mild cramping in my lower abdomen and vaginal area like when im about to get my period. I have a bit of lower back pain, not bloated, My cervix is low, firm, and open. I get a bit of white, tacky mucus discharge (no weird smell, sometimes white, sometimes slightly greenish, increased amount this morning) but generally dry down there (sorry for description).

My period have been missing for almost 2 months now (last started June 27 til July 3). My partner has had a vasectomy 8 years ago and confident he can't get me pregnant. I've taken 7 hpts ever since I missed my last period (counting 30 days from the one before that, 1 week-ish apart each, first response and clear blue, latest one this morning) and all tests were strong negatives. I have a history of irregular cycles, only had 2 periods since Feb this year, and been irregular too before that, but never more than 45 days long delay...it was only since feb cycle starts 50-60 days apart.

I have no other symptoms...boobs not sore, no excessive discharge, no nausea, etc. aside from occasional bloating and constipation, but its nothing out of the ordinary. i know my chances of getting pregnant is unlikely and i don't feel pregnant..im just really worried about my missing periods.. is this normal before starting a period ( a few days cramping) or should I be worrying? what are the odds of pregnancy? is this a sign of an ovarian cyst?