I know that I am over thinking this but what are the chances that I could be pregnant while on birth control and still had my period after not using a condom?

I take the pills at the same time every day without missing a pill. I took 2 packs in a row to skip my period last month while on vacation (which is when the sex occurred). Vacation was Feb 19th - March 2nd and I had my period from March 18th - March 23rd.

I know that if I am really worried about it I should take a hpt but I really don't think I am. I keep seeing baby/pregnancy things around that I had not noticed before LOL

Thank you!