Suggest Tests To Confirm Pregnancy Inspite Of Taking Contraceptives

I just started birth control pill for the first time on February 15th. I got my period February 1st so from what I have read the pill should have started working a week from the day I started it which would be the 22nd of February. On the 21st I had sex (unprotected) with my boyfriend and he came in me 4 times. What are the odds of me being pregnant?