I know... we can stress about everything with our LOs... I know it too well....
I must say that it's not uncommon for LOs your DDs age to be doing the 2 NF at this stage, and that doesn't mean that you have a supply issue. But it is good to rule out any discomfort from wind or teething that may be causing the NWs. Have you tried any wind meds?
Also wanted to say that it does sound like your LO is getting plenty; he's gaining weight well, finishes the feed satisfied/ not fussy (am I right?) and is lasting at least 3hrs between feeds.
So I'm guessing it might have to do with his routine, maybe he needs to be on slightly longer A times/ a 3.5hr/4hr EASY.
Could you try extending his daytime feeds, by or 10 minutes increments (whichever your LO can cope with without being too distressed) and see if it helps a bit? The way i done with DS was: I extended just the first gap between feeds by 5 or 10min one day, then kept the rest of the feeds at 3hrs, kept extending that first one until I was 3.5hrs, then I started working on the second gap, iykwim. I eventually got to 4hrs (but don't worry too much about the 4hr, some BF babies don't get to 4hrs until much later, after they're well established on solids).
In theory it should start helping with the daytime naps as well (cause you're talking about increasing A times). As well as helping your LO take bigger feeds, which in turn will help him go for longer between feeds (and hopefully between night feeds as well!!!!)
The typical A time for LOs your DDs age is between 2 and 2.5hrs, so it might be worth trying to work around that for daytime naps (have that as a guide and watch your LOs cues).
Sorry if I'm not making sense, I think I need to go to bed now...
xxx