It seems to me, as you have described, it is the being on the receiving end that is the issue. Do you have expectations about the act? I don't perceive it as an obligation.

You may find taking charge of things to be just what you need to do. You dictate the scenario and direction things go. You dictate the speed of things and how far.

How is your self-esteem, your level of self worth? Do you feel worthy of such attention? Is the denial of gratification some way of punishing yourself? Are you dissappointed you are not having sex? When it comes to oral sex, do you feel doing this is out of a sense of obligation.