Late period 😰

Ok ladies so I'm officially 20 days late and I took 3 pregnancy tests among those days. I just did the last one and it was the same result: negative.
I was taking the pill for over a year ago and then I decided to stop because it was making me too sensitive. After that, I didnt get my period for like 2 months (which can happen) but then it started again. Ever since it would always be late for a couple of days. But now I'm worried, I've been very sexually active, also dealing with problems at home, work, finals.. 
Should I be concerned ?? I hope I'm not pregnant. Has anybody experienced anything similar??Â