When does sharing fantasies become topping from bottom

[Dog's Lady]

No, he does not make me journal--we have a strange relationship: part him Dom, me sub, part vanilla, and part me trying (and failing so far) to top him. He may be afraid--my last letter was 11 sheets of looseleaf, filled front and back. We are not online-I commute from New England to FL (except when his job brought him up here to me,) so we do have face-to-face time. Just not enough--hence my backlog of fantasies. I never meant for this to be a BDSM relationship. Heck, I never meant to start a relationship; we are old friends, and his greeting used to be, "Want to sleep with me?" to which I always replied, "No." I had a boyfriend most of the time, and he was a friend who hated watching me with a (non-consensually) emotional abuser. But we got started, and now I can't tell him (my current) no. I just want to please him, whether as a bottom, a vanilla, or a top. Some of what he wants scares me, but when I think of it WITH him, it gets less scary. He was my true anal first (I tried before, but it didn't work.) He just makes everything so good that I am willing, even eager, to push my limits. He gave me my first real beating (for us, impact play with whatever toy, or just his hand) and, while it hurt, it was sublime pain. He has introduced me to so much, and taught me so much already, but calls what we do "slap and tickle." I want to learn enough to take it to the next level, which is why I was so excited to find this site. I have already learned a lot from the people-including getting an idea for topping him that I think I can do. Do Dom/mes ever have trouble hurting (in play) their subs? I love him so much that hurting him, even though he wants it, is hard. His ideas of being a bottom are so different from mine--that is where I failed at topping. I did what I would want, and pulled him completely out of sub space. I guess I would also ask for ideas for pulling his fantasies from him.
I know I am asking a lot of the people on this list, but you all seem so, well, not nice, but willing to help someone who sincerely wants to learn, that I feel comfortable asking you all for help. Sorry if I am asking too much, and thank you for everything you are willing to share.
So here is a question that might deserve its own thread: can a true sub learn to top well? If so, do you have any suggestions regarding sources?
Thanks again, all of you, whether you respond here or not. I am trying to work my way through all of the forums, but it is taking a while. But I am learning a lot. I have joined the Tasking group, as a Taskee-Would joining the Tasker thread help me?
Special thanks to Ozme-do you think started a journal on my own might help?