Birth Control & Pregnancy! ADVICE PLZ?

Hi all... I am on Ortho Tri Cylen Lo & after almost a year off being off of it, I am now back on! Here's the story: - just started taking the bc in september! I was a sunday starter so I started on sept 12 & took the first 12 pills which is about a week and a half worth of pills! On sept 24th, after missing 2 pills, I started having breakthrough bleeding, which stopped 1 wk later! It is now oct 12th & I still hv the same 16 bc pills left bc I didn't take anymore after we had ! we had 2 times in two weeks...1 time each week! I hv been feeling nauseous, dizzy & I now hv a bad cold! Today would be day 4 of my active pills but no period yet???? What is going on? How long after the breakthrough bleeding should my period come again? What is the likelihood of me being pregnant? I took 2 pg test about a week ago & they were neg... Idk if its too early or what! ADVICE.....(Helpful advise only) PLEASE