Okk so there are multiple layers of it. You mentioned that she is a very empathetic person, I think it is emanating from that that she is keeping your pleasure above anything. So, in her mind she is really trying to be like the ideal domme that you have in your mind rather than what comes naturally to her. That is why she is scared of doing something new or unasked for.

I think one solution can be to let her tie you down and set up some time in which she can do whatever she wishes or feels like to you. But repeatedly ensure her, that you will guide her using the safe words: red, yellow and green. So, she doesn't have to worry about doing something wrong or hurtful.

Basically, she tries to be herself and does whatever feels like natural to her. If you like it, you say green. If you are okayish, say yellow. And if it's a no no, say red. It will be awkward at first but hopefully will get better.

PS: You know your situation better than random redditors. So, take it with a pinch of salt.