Leona,
I've studied the photos and also the close-ups on your site and frankly I don't see any damage. The hair at the bottom is thinner, naturally, since not all hair grows at the same rate. The longer one's hair is, the more this difference in growth is magnified.
How much are you planning on trimming off? The word "cut" implies much more than a trim at your length.... hopefully you're planning on cutting not much more than a few inches. Please, please don't go above your knees or heaven forbid take it up to your waist. It's simply not needed - your hair is so beautiful as it is now.