Help! How do you know it’s real?

I am 19, almost 20, and I have been single for 4 years now. I completely forgot how a relationship works and I can’t remember how it feels to be in love with somebody. But I just met a guy and he’s a good one. He knows what he wants, he’s straightforward and trustworthy (I think) but there’s still something off. The way he kind of push me to do stuff when I don’t want to like sexy pictures, the way he keeps telling me he wants to have sex with me and the fact that he’s sometimes clingy make me think twice.

I only had one relationship that didn’t go well when I was 15 so I don’t know, am I making this up ? Is it something to worry about or does it usually go that way?

How do I know ?

Also, I’ve only been living in the USA for 2 years so the dating thing is completely new!

Sorry for the possible mistakes, my first language is not English but French. :(