I'm also into painting/drawing, and it's been a couple of years I think since I left doing portraits of humans or animals. It's a complex issue I've read up on alot, but what I have read is that this would be permissable. I do it myself, if a landscape require figures I keep them very simple and distant, limited to a few brief brushtrokes with no facial features, just to give an idea. This belong to the category of why cartoons or dolls are permissable, as they are not directly imitating the creation of Allah swt, as anyone could tell they are very unrealistic.
This is what I have read, Allah swt knows best.
Here's a link explaining it more: