Sex with my bf

I’ve been dating my bf for over a year now. We do different things often, but it’s involving him being dominant, which both of us enjoy. When we first started dating I orgasmed while he was fingering me, since then I haven’t orgasmed with him. Only when I’m masturbating. I think I feel I want to please him and it will take too long to make me cum and be too much work. How do I bring this up to him? Is this a problem? Should I do something different? What is some advice??