That's not a bad idea, but I'd be worried about how to tell if that person actually donated and isn't bluffing to get free art.

It does not matter if you are "professional" if there is a demand for your work and people are willing to pay for it, get paid to practice more! Also, considering you have probably been drawing the majority of your lifetime to get it to look as amazing as it currently does, you are a "professional" the only thing that does not make that official is the fact that you are not charging people for the work, and making it your profession. But the charity thing is a good idea until you feel comfortable with charging people. But there needs to be proof that they donated to said charity before you start there commission.

personally I think your work is cute and worth money

So...you do art trades? :o

I would happily pay you to draw my character. Your art it so freaking adorable ^.^ <3