You may want to try crossposting to /r/asktransgender , you'll probably get more responses. I'm not a big fan of that sub anymore, but it is still useful for folks earlier in transition. I'm not a guy, I'm a trans woman so I have different experiences, but I did want to point out one thing:

Now I'm just trying to figure out if the Uncomfortable is relating to bottom dysphoria,

One thing that might help here, is to remember that in this instance it might not necessarily be dysphoria and that it is OK if it isn't(remember you did still get a sense of relief from the sounds of it). Maybe try a few different options. It takes a while for people, men or women, to get a handle on what their style is. When I got on HRT and started to need a bra, I got a really frilly/girly one and it felt INCREDIBLY weird and uncomfortable while still being affirming overall. It was just the wrong style for me, I'm more of a chapstick dyke myself and girly/frilly things aren't for me.

It might be that what you picked out just isn't the right style for you. (oh, and if it IS dysphoria, still try and find other options! My ex was a trans guy, and was understandably very picky about the style his underwear had to be. Also the texture, since he was autistic as well)