The L/XL size would definitely fit you (you're actually within manufacturer's specifications for them), though you could probably still squeeze into a S/M without too much trouble (I was able to squeeze into S/M GoodNites myself until a couple of years ago).
I have a 32 inch waist (might have gone down to 30, my weight and waist size fluctuates a lot over the course of the school year), and L/XL are a bit tight on me. You might be able to squeeze into S/M, but I wouldn't recommend it. L/XL will fit fine.
Everything in that cabinet is a four-tape diaper. I have no desire to try to stuff myself into child-size diapers.
OTOH though, there are a few in there that definitely have a vintage look to them which I kinda like. I think Carousel and Rearz Vintage have the best vintage look available right now.
That cabinet is where I grab from to change... my "stash", if you would call it that, is many cases of diapers
upstairs that I occasionally visit to bring down bags to restock the cabinet.
If you've just been wearing children's diapers, you're going to be floored when you actually try adult diapers - they fit better, they're a lot thicker. sturdier, and perform sooo much better. I understand you're still a beanpole though, this does limit your selection but ABU is working to fully cater to your size Small. Go for it!