Unplanned pregnancy???

hey guys i am 18 years old and have just started using a new brand of birth control.... middle of my 2nd pack me and my boy friend had sex... he is very big so of course he did not finish or get close to finishing in me... i am still freaking out because i am on other medications my doctor prescribed for my seizures that i'm scared messed with my pill accuracy.... i only missed one pill and quickly took double the next day... i am on my last pill in the pack and i still haven't started...i quit taking my regular pills early for fear of actually being pregnant i wanted to start early... is it just my birth control not yet adjusted to my body or am i pregnant? i'm freaking out what can i do if so to stop it??? he never was close to finishing in me and i had been on the pill for 3 consecutive days before and after sex.... am i freaking out for nothing??? please help!