Should I tell mom?

Ok I’m 15 and I’m dating a 16 year old guy that my parents really seem to like. Before I dated him I lost my vCard to a 17 year old one night stand and my parents know that and were nottt happy. I go to parties almost every weekend and my mom is ok with me drinking and stuff if I do it safely and tell her first, bc teens tend to do that. I have had sex with my bf 3 times but my parents don’t know and my mom asked me if I needed to be put on the pill but then was like no wait a few more months actually (even tho it had already happened....) I want to tell her but I’m scared to... what should I do?