BCP after 1st day of sex..also 1st day of menstrual cycle...SAFE????

hi. after reading a few posts on this site im getting curious. if anyone can comment pls...

im 25 and just started an active sex life last week. on the first day, in the morning my menstrual cycle started lightly. my bf and i had a great sex later that day (2-3 times/day for 4 consecutive days) & no condoms were used. that same night (first nite) i started taking BCP. i've missed the pills by a few hours twice. am i clear from being pregnant? my mens is gone for a few days now (it normally lasts for 3-4 days) and i am still taking the pills regularly. the other day i think i developed UTI as i was having shart urinal pains but it's gone now.

any comments please???