Could I Be Pregnant?

As a female I think there is nothing more to life then being able to reproduce, I am 19 years old and I want nothing more then for that to happen for me but I don't know if it will, you see... Like many other feamles my cycle is quite irregular and I can count up 87 days between my normal periods but since last month I have been on birth control at first with the ring and switching this month to the pill, my last session of unprotected intercourse was july 7, 2005 and since then I wasn't taking my birthcontrol everyday as I should skipping up to four pills and not starting a new pack, about a week after the 7th I began light spotting but I still took what was left of my pills and according to my bc I should have started my period july 19, 2005... Well today is july 25th and I have only experienced very light brownish red spotting, normally my periods are very heavy w/ bc, I don't know what is going on and I am not sure of what to do, is it possible that I could be pregnant?