I think that if he wants to go more slowly, you should respect his concerns and try to be patient for a while.

Speaking as a switch, I know that it's easy as a submissive to assume that you're the one taking the risks and that if anyone is going to need time to get ready for something (or get over it), it's you. However, in my experience taking on a dominant role, especially without much prior experience, is a different kind of emotional challenge. You have to overcome a lot of self-doubt, guilt, and whatever else is banging around inside your head. It takes time to learn to just flip the dom switch and take control.

I hope I don't sound like an issue of Cosmopolitan from 1975, telling you to shut up and make your man happy so he'll give you lots of babies. But it sounds like you're doing a great job of letting him know what you want and how he can give it to you. At this point, I think you just need to give it some time.