What can I do to let my mom know that she's bugging me?

That is very frustrating.While not a FtM, I do have issues with my own mother and my uality. When I told her I was , she basically ignored what I said. I didn't push the subject, becasue I understood she was uncomfortable with it, and it was good enought that she had the thought in her head. So I say you should tell your mother you know how to be a girl because you've always been one, no matter what your physical appearance was. And when the straight comment comes up again, remind her that it doesn't matter if you're straight or gay or what she has to say to grandchildren as long as you're happy. Don't try to stress the issue, but let the ides sit in her mind for a while, and gently reiterate them each time she talks about them. Don't get angry. Remember, this is really difficult for her as well as you, and it's something you'll both have to get through together.