I really appreciate you putting so much effort into trying to get clear on this with me.
I hear you on the "too much." It definitely sounds like if and when that happens, it isn't something you can kind of bounce from easily, and like it is upsetting for you. That given, I would ignore some of my earlier suggestions if anything in there seems likely or a given to create that for you. We certainly don't want to compound what you're grappling with already by putting any trauma or avoidable bad experiences on it!
I do wonder, though, if perhaps you could set aside any of what you've previously considered to be sex right now to just explore pleasurable touch in ways that work for you, and then perhaps revisit partnered sex, in the way you think of it, once you have some more experience with, and information from, that way of exploring pleasure.
It might help to know that the big parts of what most often makes sex satisfying for people for whom it is aren't things you might consider sex, or what makes sex, sex, at all. A report on this study from a colleague sums up some of it really well:
https://www.theguardian.com/lifeandstyl ... macy-study Things like the stuff mentioned there -- being fully present, being communicative and responsive, scheduling time for intimacy, expanding how you define sex, real emotional connectedness during any kind of sex, leading with/incorporating the stuff you really, really like (and for you to date, sounds like that may be masturbation: might that be something to try with your partner if you haven't already?) -- tend to be bigger players than, say, being touched in any specific way or doing certain activities.
I do also want to say that something else we know from Peggy and Dana's studies is that a lot of people having what they report as truly great sex didn't get there until their 30s, 40s, or even later. In fact, their studies found that a lot of people din't start having what they consider great sex until after 50. You are just 18, in the very beginning of your lifetime of varied sexual experience, so I wouldn't expect that you, or many other young people, will be having off-the-chain sex very often yet, simply because it is actually something that tends to take practice and a lot of learning about ourselves over time. As someone who identifies with asexuality, you probably are also going to experience some of this very differently than allosexual folks will, so if any of your expectations have that basis, then yeah, you might also want to personalize them better for yourself, you know?