I can understand your confusion, and am more than likely in the same situation as you yourself are.
I am very nosy too, so if you don't like what I ask you don't have to answer at all.
Have you only been with him for a year and a half or longer? or have you just not had any sexual relations in that time.
It is hard to convey your thoughts and what you would like in respect to being submissive and being Dominated by another.
I don't think that I would worry about pressuring him, if he has been understanding that you don't want to have sex, then you both have obviously discussed this and you can also discuss your other wants as well.
If you can't see yourself being in a vanilla relationship, then I suggest you talk to him about it.
I do know that it is a difficult thing to discuss, but it does get easier once you let it out.
Maybe you had stronger feelings than what he did when he pinned your arms above your head, but he didn't think too much about it.
Ask him about it, and maybe discuss some more things that you would like.
Show him stories that turn you on. Talk about things that you think are sexy about being Dominated.
You don't have to come out and say that this is what I want now, but let him know that you find these things a big turnon and you might like to try them if he does as well.
Start slow and proceed from there.