Short answer: No.
Long answer:
1. 5'6" is not a grossly unusual height, you need not be so self-conscious. There's no surgeon in the realm who'd dream of operating on you, the risks of surgery would far, far outweigh the benefits of losing 2" off an otherwise totally normal height. When leg-shortening surgery is performed, it's for people who have legs which are significantly different in length from each other...
2. NO, a low protein and low calcium diet would not make you any shorter, and would be very bad for your health overall. Calcium intake and bone integrity are not laughing matters.
3. If you're not trolling me, then you should speak to someone about this, because to even consider ways to... Shorten.. yourself.. is really concerning. Certainly nobody would seriously ever perform surgery on you just for the sake of being able to wear bigger heels.