I think wanting to give your hair to Locks of Love is AMAZING!! I have super short hair ( I use hair clippers w/ a one inch setting and do it myself

) and have never had enough to donate to anything except the garbage can

.
I can tell you my hair was almost shoulder length when I shaved it the first time, and it took me a minute to come to grips with it, but I was so much happier after I got rid of it.
I guess it depends on how badly you want to get rid of your long hair. Do you think about it every day? Wish there was a way to make it go away without having to pull it back? If you answer yes to those, then go for it! Get a super cute Bob hair cut and say hello to the new you! Hair is just hair, it will grow back (unless you have a skin disease, which clearly you do not ) so if you don't like it, it will grow long again about a year or so
Hope that helps, have fun in your hair pursuits!