Sure have
What worked for me was getting on a low heat, and low manipulation regimen. Basically once a week I washed, deep conditioned and rollerset my hair without fail. During the week I would moisturize and oil my hair to keep it hydrated and to protect it from breakage.
IMO you can definitely get your hair back to a healthy state without a drastic cut, you just have to be willing to make the changes in your regimen to get you where you wanna be. You mentioned that its hard for you not to use any heat, but if you are abusing the blowdryer and curling iron on already damaged hair, that's just gonna lead to more damage. You should really try rollersetting if you haven't tried it already. It's a great way to acheive the straight styles w/o all the heat damage. Also what might help is to do small trims every 3 months or so to get rid of the damaged hair instead of a huge trim.