My boyfriend wants me to take control during sex, I'm really shy?

Recently, my boyfriend has started asking me to tell him what I want during sex. He asked me over and over and over and eventually I was running out of ideas of how to answer lol I don't really know what he's expecting of me? I can initiate sex, I am very vocal during the act, and I can be kinky... but this made me clam up for some reason? What is he wanting?