I appreciate the work, but as one of the active member of the charity of the one you made for this logo, I guess you need to enhance your skills regarding the work as I see it as not visual or remarkable.
You might need to consider that the charity is bitcoin related so it should have been related to that, as for charity symbols and font selection also matters.
Anyway, seems I sound demanding for a free offer but you can keep it as idea for your future clients and offers. Cheer up.
As one of users who requested a free avatar here, I would like to leave a comment for OP.
It is true and honest comment. The temporary quality of designed avatars is not good. I don't say it is low because I don't want to kill OP's motivation. Everyone need to start from somewhere, on the forum from newbies, or from any services like signature or avatar designs.
Keep practicing and you will do improve your design skills. Some day your design skills and your works will become much better. I don't know why you choose graphic design because it does require creativeness that is the most important thing to help you achieve something big. Without creativeness, you will not going nowhere farther.