I've been having unprotected sex with my boyfriend for a couple months now but i am on the depot birth control. this morning i had spotting. pregnant?

Unlikely: The failure rates for depo-provera are quite low, on the order of 0.3%. It's not unreasonable to check a urine pregnancy test to be sure. It's also not uncommon to have spotting while on this medication - in fact, it's probably one of the most common reasons for stopping this medication. If the bleeding persists you should contact your doctor. Best of luck.