I'm sorry for your frustration and guilt, which I think you describe beautifully. Owning a seriously reactive dog is tough. Sometimes it's amazing, sometimes it's just plain awful, and there are a lot of points in between...it's a roller coaster, and eleven months is likely to mark an especially low point. So if it helps to hear, I expect that things will improve for you as your teenager grows, matures, and (eventually) settles into herself, truly. And honestly, I think it is normal for our hearts to hurt when we love a dog so much, but don't feel like others get to see what makes her great.
FWIW, I have found more helpful online support in forums and mailing lists that are specific for reactive and/or fearful dogs, where the other people on the list are likely to have first-hand experience and more specific knowledge (and a much lower propensity to advise downright toxic things). I'm sorry to say that my resource list is probably out of date...there used to be a couple of good Yahoo mailing lists (shyK9s and functional rewards, the first aimed mainly at severely fearful dogs, the second a probably-defunct BAT-focused list). I think Facebook groups have probably replaced these, but I don't know for sure...maybe you could ask your trainer if s/he has any online reactivity communities to suggest, or maybe someone here has more up-to-date recommendations?
I know you weren't asking for advice, but two good books I like are
Control Unleashed (either version) and the new
BAT 2.0 book. You might already have them, but if not, they can really help offer a good framework for understanding and treating reactivity (and associated things, like impulse control) over the long-haul, and helped me a lot when I was struggling with my first dog, who was also severely reactive and more than a little bit heartbreaking. A good trainer helps even more, of course, and if you're happy with yours, then that's such a great place to start.
I think owning a reactive dog is an opportunity to let go of the idea of what dogs "ought" to be like, and that can be a painful process. We think dogs
ought to like to going out to the park,
ought to like visiting with people,
ought to be a part of every gathering, and so on. But of course, as you know, not all dogs do like those things. Some dogs are calmer, and happier, when they are in familiar surroundings, when their social circle is small, when we enrich their environment with things like stuffed Kongs and scent games instead of visits to crowded parks, and so on. Finding the right balance for you and your dog can take time, I know, but it can also be something that brings you closer together in the end. Small comfort, maybe, and you have every right to vent once in a while! But as we let go of the idea of who our dogs "ought" to be, we get to see them more as they truly are, and sometimes I think that takes us to surprising places.
My current dog also used to bite hard enough to draw blood regularly. Oh, I do NOT miss those days!! Congratulations to you for helping your girl learn to use her mouth more gently...I know first-hand how it's so much nicer to live with a dog who doesn't leave you with an embarrassing set of bruises and punctures (to say nothing of the pain). It sounds like you're working with your girl and seeing good results, just that things are happening at her pace. That might be a slower pace than you'd like, and it almost certainly is going to be a slower pace than random people over the internet think "
ought" to be happening, but as long as it's steadily working toward building a solid relationship with your dog, I think you're on the right track. Exposing a dog to triggers is not the be-all, end-all of living with a reactive dog (or even necessarily a good idea at every point). Setting up controlled situations so that a dog can have positive experiences around her triggers is important, eventually, but so is finding ways to have fun with your dog, to play games with your dog, to enjoy living with your dog.