It's completely normal to ask "what ifs"! It's how we work through things in our head.

But.

You need to answer your own what ifs.

"What if he doesn't really like me for who I am" - I doubt this is the case; you don't seem like a shallow person; you're pretty good at expressing who you are and what you want. I'm sure he's gotten to know you on some level. "If" he doesn't like you for who you are then what is he doing with you? It's not a factor you should worry about.

"What if he is just desperate for a relationship". You haven't suggested anything that would make him come across as desperate. There are plenty of women out there and if he was doing it for desperation he would have left by now.