There's a lot to unpack here. You have a point - but only from your perspective, from the details you've given us here. You don't say whether he goes down or not, which is important as you mentioned reciprocation. Mostly, the conflicting details here are what's confusing me. But I do get what you're saying in the sense that I've given blowjobs that I really enjoyed, and that I've given blowjobs that made me wish I could teleport. Have you discussed this with him? If not, do that, and leave out the details in your second paragraph - nobody wants to hear that about their body.

Other advice:

• Suck his dick on a bed/couch or put a cushion under your knees, so that they don't ache.

• Get tested for TMJ.

• Ask him what he likes so you're not down there for too long.

• You don't have to swallow, and having a chaser nearby could help.

Also, I really don't think 69 would work if he's not feeling it. You both have to take off your pants, at least. Might as well just fuck, which isn't what he's going for.