Slut shaming myself

So tonight my bf and I decided together that we were going to take it to the next level. Oral sex. So I am a super shy person so I was surprised I did it but I felt comfortable doing it in the moment. Afterwards on my drive home I felt like such a slut and can't believe I let him take my shirt off and blah blah. Did anyone else feel this way at 20? Also I am super religious so that probably plays a part I'm it too.

IMPORTANT: My bf didn't make me do anything I didn't want to and made me feel very comfortable. He continually asked if I was alright and stuff. My ex has messed me up by saying if I left him no one else would want me and manipulated me into having sex with him but saying if I lived him I would do this and that with him.