Missed periods

So back in may I missed my period for 2 months then it came back during that time I took pregnancy test all came back neg. Now currently……my last period was in October. Haven’t had one since. I have taken 2 pregnancy test about 2 weeks apart and both was neg. It’s been a little over a week almost 2 weeks since I took the 2nd one and I still haven’t started my period. Any ideas, has anyone else ever experienced this before. I’m currently waiting on a referral for a obgyn for a pap-smear. And I’m going to talk to the obgyn about it. Just trying to see if anyone else has experience this before. And could give me a little insight on what may be happening. Tia