Please help?

I am 19 years old; and currentyl unsure if i am pregnant. I started the contraceptive pill yasmin 3 weeks ago. my periods are due in 1 week. i recently had with my bf and he withdrew but i think he began to ejaculat as he did so. do u think i cud be pregnant? please help. i need answers as i dont no whethre to go get the "morning after pill" as its only been 48 hours.