Any chance of pregnancy? Plz help.

I have a old history of thypothyroidism and recently diagnosed with PCOD on USG. I am unmarried, virgin and never had a proper penetrative intercourse but had some activities like genital rubbing, fingering. Last activity was 3 months ago (around 6 sept) After the meeting I got light period (30 sept) and googled the cause, it said it might be pregnancy. I did UPT and b hcg on 8 oct (negative). Then I did several UPT after every other day (negative).Then i got my period on 26 oct. Again did b hcg on 30 oct (negative). Went for abdominal USG on 11 nov (no pregnancy seen). Got my period on 24 nov. Again went for abdominal USG on 30 nov (no pregnancy seen). But I why i am getting signs of pregnancy like linea nigra and increased stomach size. This is so confusing. I am extremely sacred and anxious. Is there any chance I might be pregnant?