Deigja, consider what Aussiegirl said about writing down your fantasies. If you don't want to do fiction, think about filling out a limit questionaire. There is an example here. This will give him a few more ideas of what you like/dislike without telling him exactly what to do.

When I was first learning to Domme, I was unsure about how far I could go and how hard I could push. I questioned if my partner really liked it or if she was just doing things to please me. Only once we built up trust, did I gain the confidence to give my partner exactly what both of us wanted.

You might want to also consider the traffic light idea of safewords. I use red, yellow, green. By having a 'slow down' word and not just a 'stop right now' will give you a break if things are going too fast. Having a 'keep going' word will give him a chance to check in without breaking the mood.

I can only the echo the other posters in telling you to be patient. You have been frustrated by the posers and wannabes in the past. Don't mess up what you have finally found by pushing him too hard. Be patient and you will be rewarded.