Making it official

So I’ve been seeing this guy for almost 4 months. In the beginning I did tell him I wanted to take it slow because I’ve had issues in the past with commitment. My issues stemmed from situations where I became serious with somebody and then was cheated on. So I have a slight fear. And I openly expressed this to him and he was understanding about it. So for the past few months has been nothing but great and I think I would like to take it to the next level and make it more official. But I’m not sure exactly how to go about it because I want to make sure that he feels ready since he knows about my previous issues. How would you guys go about it? It’s also much more difficult being an adult because it just sounds very childish to ask if he wants to be my boyfriend 🤣