Nervous and Vulnerable

Today is the morning of my rendezvous with DrPeter.  There is a major difference this time which has been feeling more nervous than normal and weirdly vulnerable.   We had talked months ago about me topping him, and I said at that time I wasn't feeling into it.  I talked to my Master about it too, and he basically left it up to me.  He wasn't going to prohibit me from doing topping, but he wasn't going to order me to do it either.   So I just put in the back of my mind as a "Nope" and it simmered there, but then last month it started coming to the top of my mind as a "Maybe I could..."
I thought about it for a whole week before coming to the decision that I was going to try it.  Then it took me another two weeks to come up with the courage to type it out in a message.  I have to face a lot of fears in deciding to do this.  Maybe it will turn out to be no big deal at all, or really fun, but I have a lot of fear.

What if I start but then I get angry? (Why would I get angry, well, I don't know, only that the few times my Master told me to hit him with an implement, I felt uncontrollably and unreasonably angry). What if I feel sick to my stomach?  What if I feel angry and sick to my stomach?
What if I am bad at it?  What if I hit the wrong spots accidentally?
What if I find it totally unarousing?  What if I'm good enough at it that he wants me to do it all the time and I never get my turn for being the bottom again?   What if it makes me change my view of myself?