how long were you on the pill at the time? people say different things but even after 5-7 days there is supposedly some protection, depending when you started. i think the odds are probably against you being pregnant, but yeah it's possible. some people do still have bleeding when pregnant, pulling out is indeed not reliable, etc, all stuff you know.

i would guess it's more likely the various hormones have just screwed up your cycle. but if you plan to keep it (if it exists) i wouldn't take any chances just yet.

i hope you get the answer you want