Birth control pills, pregnancy chance, I am so confused :(

this is a little confusing.. this month, on july 8th, i started my period and planned on starting bcp's on the following sunday. that sunday about an hour before i started the pills, i had unprotected sex. (my period had stopped.) he pulled out, and did not ejaculate until later. i figured if i took the pills right after sex, and that i had just finished my period, it would make chances pretty small. it has been a little under a week now, and i work outside painting buildings outside. i have been very sick every day because the pills make me extremely sensitive to sunlight. (serious migrains, eye pain, nauseausness, just all around bad.) I have not had sex since that one time. however i think i'm going to stop the pills today. I have taken about four or five. my question is, how high are the chances of pregnancy, and what should i expect for a period and when? I'm really nervous. :(