Can't handle his penis?!

So I like to hear if you had experience something similar and how it's developed with the time.

I meet a guy like a month ago. I liked him. He liked me. And, since the day we meet, we didn't stop dating.

We spend the weekend together. Everything has been perfect, I'm very comfortable with him and viceversa ... Now, the sex.

I always have been with guys with normal or more like small dicks and he has a long plus thick dick. I was like : wow good; when I saw it BUT! The sex was pretty intense for me.

Is not that it hurts, but I couldn't really help but move out, instead of deepen the penetration. I even told him to grab me as I didn't wanted to do it, it was a reflex, and of course he wasn't sure of what to do, and was constantly checking if I like it or if I wanted it more slow or directly stop.

Now I'm thinking if that is cause I'm not used to have sex with a big dick and with time I will stop that reflex of running away?? Also, I have never been a loud moaner but couldn't help myself and moaned very loud. Don't get me wrong, I'm happy with all this but at the same time worried. And I think is the same for him, his proud but at the same time worried when I told him that i can't help but move out.

So did you have similar experiences?