What does "parents won't let me pay for a sports nutritionist" mean? How old are you? If you are Genuinely going to pay for it out of money you have earned, how can they stop you? Or do you mean they won't pay for it?
Either way, to be honest, that statement is putting you in an age category where you may well still be growing and you are certainly still developing in terms of eg bones. Restricting your diet at this sort of stage in life is probably not a good idea - not to the extent you are talking about. Just eat a healthy balanced diet and try to sort out the injuries.
Also, if you have the money for a sports nutritionist, would it not be better spent on a physio to get you fit again?