I personally don't understand the concept of compression shorts on a bike.

I have a couple of pairs of cycling shorts that are tight on me, but not as tight as a good comfortable fit in compression running shorts. For cycling, it means the chamois doesn't conform to my body, and they chafe. A lot.

I want cycling shorts to fit like a second skin. That's important where my real, and pretty delicate, skin contacts the saddle.

In shorts, I'm a small to medium in PI, a small to medium in SheBeest, an extra small in Terry (I think anyway, I've never actually tried on their XS but my small pair is so big that I can't wear them), a small to medium in Castelli, and a medium to large in Etxe Ondo. In LG, I'm a perfect wouldn't-change-a-thing (except maybe making them a little shorter) Large.

It sounds like I'm built similar to you. I've got some pretty substantial saddlebags, and pictures of me at foot races look enormous.