Hey, I'm really sorry that I didn't get a chance to come back to this thread sooner, but I was going to suggest this very thing. Sex creating anxiety in people, even people who don't have an anxiety disorder, is not at all uncommon. However, for people with anxiety issues, it can seem that way, which, in turn, causes its own anxiety. Lovely, eh?

One thing I've found, is that with anxiety, in general, that is in any situation, not particularly for sex, if I tell whoever I'm with, "this is starting to make me anxious," I pretty quickly calm down. A lot of the fear is the whole, "what if I completely lose it in front of this person," which again, causes its own anxiety. Once I get the sense that they're "on my side", and if I DO lose it, that they're there for me, that in itself can be very calming.