late but short period?

my period came 10-11 days late, I got it Wednesday morning and it's Friday afternoon and it's already stopped. I had a lot of mild cramping, and my periods usually last 5 days. I am sexually active, I'm also on birth control, but I don't take it at the same time everyday. I've been on birth control for almost 3 months, I'm on the last week of my second month pack. could I possibly be pregnant?