That looks really competent!
Full colour up-close portraits are challenging at the best of times for me. It's one of the areas where I find I can spend HOURS noodling around before I get something I can stand back from without totally cringing.
I guess that's a good thing; it's always nice to have a challenge wall to push against.
Anyway.., have you ever tried Clip Studio Paint?
I tried Krita, and while the software package is nicely laid out and has lots of great tools, my computer was having trouble with it; fast strokes on a big canvas resulted in cursor lag which drove me nuts. -Other users haven't had the same problem, so I don't know what the issue was. Maybe something bunging up my OS..? -My computer should be fast enough. Either way.., Bummer!
Luckily Clip Studio Paint works really well on my system. It's lovely to draw with; it has an excellent brush engine which puts it head and shoulders above the crunchy-line Photoshop when it comes to inking line-work for comics. Unfortunately, it's also paid software, but still far less expensive than Adobe products. (I got my copy for around $50 on sale.)
I've tried Clip Studio, but only the trial version and while it work nicer than Photoshop, I didn't want to spend money on it because I seldom draw comics. The way I see it, Clip Studio works perfectly for comic/ manga enthusiasts or creators, but Krita is splendid for illustrations. But we all have one software that we must be really good with.
There was a solution to lagging Krita, which was to disable OpenGL. I never had any problem with Krita. It used to be hard when it first came out, but nowadays it feels natural because the interface is much better.
I seldom draw portraits because it's not really my cup of tea; I've got several friends and acquaintances whose works consists mainly of portraits though. It's a good money maker though IMO because from where I come from, people mainly ask for their faces to be drawn heheh.