Sweet photo! I'll give some feedback:
keeping in mind that there are no hard-and-fast rules in photography.... they're meant to be broken (sometimes). But, I usually try to avoid backlit subjects. It's not a bad effect in this case, especially with how the fur on the left gets lit up.. that looks nice to me. But then you have the problem that the background is way brighter than your subject, and the viewer's eye tends to go to the brightest part first. And you could post-process doggy's face to be brighter, but there's only so far you can post-process lighting stuff like that before it starts to look a little fake.
I agree with others about always shooting in raw. I just switched to Linux so I'm in your boat--but if I can't get Affinity working in Wine, I'm going to use something like Darktable to process my RAW files, then import into GIMP for further processing. (I do hope I can get Affinity working though... it's not supported in linux but I think some people have had luck. GIMP will do, but, meh.)
Side note, I like shooting in aperture priority mode. That way I can plan from the get-go: what do I want to be in focus here? If I want just the subject in focus, and everything else blurry, I'll open it way up to f/2.8 (or however wide my lens goes). If I want the background in focus, I'll go to f/8 or f/11 (keeping in mind what Kevin said, you start losing a little sharpness if you go much smaller than 11.. but, you won't notice unless you're printing big, most likely). Also like Kevin said, if you have a shallow DOF (wide aperture like 2.8), likely you'll only be able to get part of your subject in focus. Heck, even at f/8 when your subject is this close you won't get it all in focus (as you can see from doggo's nose vs eyes). So, it's a tradeoff. part of the fun of deciding in the moment. :)
For me, post processing is half the job. Or more! Taking the pic with your camera, your main job is to focus, get your composition basically right, and get your lighting basically right. Some of that stuff you can fix in post, but if it's all good, you can really use post to make something magical.
Anyway, looking forward to more pics!