How to make sex better?

So I’m 20 years old, only lost my virginity recently(well like back in October) haven’t really had sex since then. The person I lost it with was a complete stranger which is fine with me. But honestly I kinda felt like shit afterward? Even during? I’ve tried having sex with other guys but I just can’t bring myself to do it. Even a old ex of mine and I have been hooking up but when it comes to actual penetration I don’t really wanna do it. It’s fine when I do it to myself but I don’t want anyone else to do it. Even when I do do it to myself it still sometimes hurts? And I don’t feel too much pleasure from it?? I just wanna know if anyone has any tips for me or anything. Gotten to the point where I won’t even masturbate anymore.