How would I know if I'm late? I'm off BC.

I got off Birth Control last month. I had the 21 pill pack. After I finished I got my period 4-5 days later on CD25-26. When I was on BC that's when I got my period. Off BC I got it CD35. When should I expect it? I'm not CD21 and after my period April 22-May 2nd I had unprotected sex(him ejaculating in me) every second day.