I almost hate to reply to this one.
While I think it is an interesting subject, I don't think I would mess with shooting homemade black powder unless there was no other choice like in a survival situation.
I don't feel I am at all qualified to say if your powder is safe to shoot. I'm not sure why you can't get store bought black powder but that would be my choice for sure. The only advice I have is if you are going to shoot it anyway start out with small loads, very small loads.