Hi Sietz,
First I think it is great you are exploring this rather than rejecting or resisting off hand.
I did one session of hypnosis long time after I had a crazy experience in the middle east (after vacationing there) and it was actually relaxing and good and weirdly knowing I have PTSD...what came up was quite surprise to me.
I will share a bit of my experience and then comment on your trepidation.
What came up for me (after all I went through in my life) was a moment in time (around 14yrs old) when my mother left my dad temporarily and how scared I was. Even though my mom is the biggest abuse in my life, when she finally left us with our dad, apparently I had sort of breakdown that convinced me family unit is a fake thing not a real thing because it could breakdown just like that! I got stuck on that feeling during 2.5 hours of hypnosis. None came about my abuse or other things. Weird when I think of it now. Knowing what I know in therapy now!!!! but they go by your mood and what needs to crack at that time. At the time, the only thing I shared with her prior to the act of hypnosis was that I feel lonely and would like to find love but just do not attach properly. I mentioned very high level of my past (I was not open about my trauma much then).
Now for you, you have been therapy for while so it is possible that you are closer to the core of your defense system - the holy grail of your PTSD (only you can feel and know how far you have come or not)...so it is possible you are afraid because you are not ready to let go what you know about your state of mind.
While you are thinking about it, i hope you also try to imagine as it being fun and you learning something so new and so important and of course it can also go wrong that you may recall something you do not want to.
I wish I could alleviate your worries but it is hectic. I have had weird sensations many days afterwards.