might be pregnant ?

Elli • Elli~ 19~Midwest but east coast raised~lover of memes and dogs~wiccan~self-deprecating hipster
So me and my boyfriend had unprotected sex for the second yesterday (I ended up getting my period two weeks later and even took a test to make sure, which came out negative. I also started the pill right before my period started and he also didn't cum inside of me) 
I'm a little paranoid, because I've been on the pill for about a week and a half and I know that it doesn't work as well if you don't wait a month before having unprotected sex. He also came inside of me this time, and in the past he's had 100% unprotected sex with other girls and never got any of them pregnant so he thinks he may be sterile, though I don't want to bank on that since women in my family are extremely fertile. 
I also just finished my period last week so I'd technically be in my fertile window if I wasn't on the pill. I've thought about taking a pregnancy test but I know it's too early to tell. 
I'm not sure what to do exactly, whether I should tell my boyfriend or not? Or if I'm pregnant if I should tell my parents (who still think I'm a virgin and would be pissed if they found out otherwise) when I find out?