Too shy for my liking

My boyfriend is very dominant and I’m super into it. He always says things like “tell me what you want?”

Or “ask me for it” and I always have replies in my head but sometimes I get nervous or something and can’t spit out the words I want. I feel like I’m shy in this area but I don’t know why bc we’ve been together awhile and have known each other for years, and I’m the one that’s into being tied up, blindfolded, and dominated. Any advice on how to get past it, and spit out my freaky responses?