you could indeed try protective styling. And also your hair will breaks more easely when you dye it. And do you do some Deep treatments and/or prote´n treatments already?
I don't know about bodybuilding and hear growth, but I know bodybuilding affects the body (for example: hormones, low fat percentage), and therefore maybe the hair growth too (altough I understand you don't stop doing that just because it maybe, might have a little effect on your hair, haha).
But, it is possible that your hair will not grow so long. Everyone's hair cycle doesn't take the same amount of time. If your hair is very healthy but still doesn't grow longer then a certain point, it could be that it's just the natural, 'terminal' length of your hair (instead of breakage)
If that's the case, you could try braids to stretch your hair, you'll see the lenght better but it will be less curly. But, in my opinion your hair is very beautifull and not short at all!
how often do you cut it?