Hey, Blender is always a good place to start.

And you don't have to feel constricted to do 3D low-polygon models. Sculpting isn't a bad start, and Blender's sculpting is decent. :)

As someone who has a bit of experience making their own models, it takes a bit of time and knowing where to make the split between certain parts of the body to make way for no weird clipping with custom-made stuff.
I would gladly hand over a model that I made recently if you want to see what it could look like and how it flows.
Obviously you'll have your own style of doing stuff and that's alright.
It takes time for sure and I commend your efforts even if it doesn't fall through in the way you hoped.

if it would help, i have a body model that fits a good chunk of your oc's bodytypes (or can with slight adjustments), only requiring the head to be made :p