I think Jtrash put it perfectly. There isn't anything wrong with working from a base.
The thing with tracing is that, as a technique it really comes down to how it's used. Until you've become accustomed to understanding the fundamentals of art it's not a good idea to trace until you understand how to do it in a way where you can use it without it being a crutch that can be obviously seen.
Otherwise it kind of runs the risk of plagiarism. Unless you're intentionally making a shitpost this is why it's encouraged to avoid tracing for the most part. In this case however, you're tracing over a base for reference that I'm assuming you created.
jthrash
Using a generic base mesh for pose and anatomy reference and adding your own details, outfits, facial features, etc. is not only allowed, but encouraged.
I think it's only a problem if you exactly trace over someone else's character without making any changes or just AI-generate the whole thing, but using a "generic anime girl" base mesh no one owns the rights to and then adding tons of unique details until it looks completely different the "generic anime girl" base is perfectly okay. Masahiro Sakurai basically uses a "generic anime boy" and a "generic anime girl" figurine to help his team animate for Super Smash Bros, for instance.
From an artistic standpoint, though, using the same base mesh over and over can result in one's characters looking the same, having the same face, same body type, all that. You might want other base meshes to draw over, not just that one girl, for more variety.
Finasty (Updated )
I do use some models differently depends on what character i am drawing, if it's a teenager, then i use that base model, if it's a small child them i use a small girl models, same goes for the mommy and the rest
Edit: Some small mistakes made by the pose, i usually fix it so that it matches with my style