You haven't really said if you mind taking care of your long hair, or if it gets in your eyes, bothers you. If all of that is OK with you, I think you should go with the suggestion of trimming it until you have 10 inches and make the donation. This will give you more time to think about what you really want to do, and at the same time you make a donation to an organization for cancer stricken children. Your hair looks like it is really healthy and thick, probably a great donation for locksoflove. And I agree, don't go with short just because of what other people say.. Hairstylists like short because you have to maintain it more often than long, and most people just don't get long hair. I have always liked long hair on guys..My DH's hair is almost down to his belt...(although him-50 years old- I think maybe a short haircut might make him look younger..) Brad Pitt is positively yummy with long hair..
Good Luck!!