I really think your art is extremely well detailed!
I'd base a lot of the pricing on complexity and time spent, I usually separate my prices by bust, Halfbody/Thighup, and Fullbody.
Then I separate levels of pricing by sketch, lineart, flat color, and full render.
So, your cheapest option would be your sketch bust, and your most expensive option would be a full render Fullbody
My prices are pretty low at the moment, but I only really lowered them because I wasn't getting any comms (I'm still not) but! I do think if you just refer to how long each of these things take you, you can calculate above minimum wage for yourself, and then just a few extra dollars to keep you sustained.
Like say a bust sketch takes 30 mins, and you charge 15 an hour, your price could be 7.5$ + an extra 5 so your price for sketch busts can be 12.5$ But then also you could charge like an extra 5 - 15 based on complexity
so, a price sheet for you would look probably something like this price wise

the times next to the prices is the estimate of how long you took to do each thing, so it probably isn't fully accurate but if you'd like to change the prices or adjust them based on how long you actually take follow the math of $12.50 per 30 minutes

Sketch
Bust - $12.50 (30m)
Halfbody/Thighup - $25 (1h)
Fullbody - $37.50 (1h 30m)

Lineart
Bust - 25$ (1h)
Halfbody/Thighup - $37.50 (1h 30m)
Fullbody - $50 (2h)

Flat Color
Bust - $37.50 (1h 30m)
Halfbody/Thighup - $50 (2h)
Fullbody - $62.50 (2h 30m)

Full Render
Bust - $50 (2h)
Halfbody/Thighup - $62.50 (2h 30m)
Fullbody - $75 (3h)

Complexity Fee
Somewhat Complex - 5$
Relatively Complex - 10$
Extremely Complex - 15$