Kinda worried but at the same time not

Okay so I started the pill almost 3 weeks ago and the day I started my pills me and my bf had unprotected sex and he cummed in me but I took the pill that night but everything just says to not have sex on the first 7 days of the pill cause it won't protect you. is there any chance that I could be pregnant? Me and him have sex regularly and he's been cumming in me a lot lately since I'm on the pill he just goes ahead and does it. I've just been gaining some weight and getting a little nauseous and some cramping and sore boobs but I just thought that was from the oulk