I'm not sure what it is that is a concern... it seems all good to me. You have a friend and you get to have sex with them without complications of love and partnership... *meh* go for it and just enjoy. It will change when it changes and unless your feelings change before that time I don't see why you would have to even dwell on what you are doing.
Congrats on the new body to explore. I remember exploring PN after a 10 year break from men... There are just different ways for doing it, but it all ends up the same... the journey to orgasm or someone else's is just different. Each erotic and exciting and fun,,, just different.