The word "slut" is an irrational word to describe and insult womens sexuality further. As someone else said, it is not a bad thing to explore your sexuality. If anything, it is a GOOD thing.

My main worry is that you feel this guilt for being sexual with someone, and not because you feel dirty etc but if he manipulated you in a way to share photos/videos you weren't ready to share when he requested. Please make sure you can break that down and see how you feel.

17, 18, 19, etc, age doesn't describe the capacity the ability to experience or understand emotions/attachments. You are completely validated in your emotions and experiences, no matter the age.