My mom thinks I am a ?

I was and still am I good girl I started dating at 17 and was in a serious relationship for a few months I told my mom I lost my virginity so we can go to the doctor to get the right protection. Me and him broke and and I started dating someone else who I was never so crazy for I guess I was just rebounding him. We broke up last month and now I am dating someone that I really like a lot. But to my mom I think she thinks I am a even thought I'm not. I came home tonight with a hickey... I know bad move but she knows I was with the guy I am dating now and she knows how much I really like him and my mom actually likes him. But she thinks I'm planning on sleeping with him when that's the last thing from my mind... How do I explain to her I wont do anything like that for a longggg time. Because I know the responsibility on the relationship after.