no, you arent the only one. i have clients with prior health

issues and dont cum/and some dont get hard but still enjoy all activities that they can do.
 the first couple of times this happened i did feel like "what am i doig wrong here!!!" but after open discussion with my client all is understood.  I think if you are open with the provider in the beginning is the way to go.(not in an appt request email i would do it at whatever appropriate moment when you are getting intimate)  At least for me it allows me to relax more and therefore enjoy our time together.
really no big deal at all, remember our goal is to do what pleases YOU (and its a super plus that we get to enojoy as well )