Also going to be highly TMI. The big red X over there to your right, that's your opt-out lol.
YMMV, but for me the sweet spot is on the very edges of my glans... that kind of outer-rim area comprising the "German helmet" portion squarely between the glans and foreskin (and it has to be lubed sufficiently otherwise there's just nothing... so I hope you're trying all the tricks to figure it out. If proper lube is too expensive, I use a bit of olive oil and it works great; not toxic or harmful either). Soon as I could easily access that I couldn't reach touchdown right otherwise and would get very frustrated when I for whatever reason couldn't get that same level of sensation from it. A large part of getting to that is actually being very hard and sometimes I simply can't stay that way all-through (the brunt of that is mental though; that takes practice to keep all the damned nagging thoughts out to be able to really let yourself go). When that happens, the trick I've found to more or less remedy that is to lean over a bit (gravity can be your friend indeed) and bear/tense down (this should go without clarification, but make absolutely sure you don't have to "go" first) for me that firms things along nicely. However, on the last couple of days of my dose it just won't happen no matter what I do. It really needs the appropriate T levels to get and stay hard. Without the hardness there it's just... not worth the bother trying, honestly. I'd rather wait (being a snappy, even waspish ass... I really don't mean to be but that's just how it is) the few days; makes everything a hell of a lot more intense anyhow.
Uh... if it doesn't make you too dysphonic, the nipples help. Mine are directly (and I really mean, DIRECTLY) wired to that part of me (makes it twitch and the whole 9) and are even more sensitive from the T; in fact, I could actually feel this direct 'Y' route in my nerves from them to there being established about 2 months into T (before T I never really felt much of anything in my erogenous zones so this is really all new to me. Sure I did the deed myself before but it doesn't begin to hold a candle to what I can feel and do now). Now I don't like those areas very much for other reasons, of course... but I also can't get a decent overall sensation unless I'm... stimulating... that bit occasionally as well. I catch myself subconsciously doing just that in the morning while just waking up (morning glory can be a real *COUGH* at times)... I don't really like it because of other connotations but honestly, it's what works and so I frankly don't give a damn. And for that I'm concerned about what top surgery would do... I hope I won't ever lose it but I suppose if I did, I'd learn to get over it. Or perhaps they will finally discover a method to preserve that particular sensation before I do. Don't know, and that's so far off I'm not terribly worrying about it yet.
At the end of the day, erogenous zones are tricky and different flavors of bastard for everyone. The same tricks won't work on every dog. It really is a matter of exploring yourself and experimenting. And actually, many problems in this area are not physical but mental. You HAVE to relax and drown out everything else to do it right. And be patient. Sometimes, I defeat myself because I want to hurry up and just get it over with and the result is a very poor finish indeed. But when I'm really, really patient about it that's when the TNT happens. Drive yourself almost to that lazy finish, but stop. Repeat and repeat.
Oh and, that bit directly in the middle of the in-between area, on the topside... or again right there towards the 'bottom' edges with that triangular joining on either side... WOW. Try sliding the foreskin or the pad of your fingers over just there and see how you like it. On mine there are nerves JUST there and... yeah.
I had only just figured out the really, truly proper way to do it a few of months ago (mine wanted to grow girth before length so I couldn't really get cracking as fast and well as others might have). It got a hell of a lot longer and thicker, and so absolutely rock-hard I thought it literally might burst. That was do date the best and not to mention genuinely mind-blowing orgasm I've ever had in my entire life... I had to actually shove my knuckles in my mouth to shut the hell up before my otherwise irrepressible growling would have woken the whole house up. I mean literally "vision black around the edges" and everything.
Since, I've been frustrated because I can't quite get that right every time. It isn't near that same level of "little death" and I really want it back but wishing and hoping isn't going to get me there.
Be patient. You will figure it out again. I know I will. Eventually.
Also, try your other hand... it can heighten things.