Changes in pap and missed period

Hello I am a 25 years old, came off the pill about 7 months ago and have been regular until last month (Aug) when my period came about 5 days late (started on the 6th) . I have not had a period at all yet for Sept. At the end of Aug I had my annual pap and it came back as having minor changes and that I should have a fallow up in 6 months. I had a full STD panel ran (just precautionary not because of any symptoms) and everything was normal with those. I have taken two at home pregnancy tests both are negative and I do not have any other symptoms of being pregnant. I have never been this irregular, can the changes in the cells and the missed period be related and do you have any ideas of what may be going on? Thanks,