I went 5 months without a period, could I have done any damage? I never got cramps before, now I get one at the start of my periods. I was anorexic a couple of years ago.

No damage done. You may want to try a vegetarian diet with lots of fruits to correct the imbalance when you were anorexic.
It. It is unlikely that not having your period will have any damage. The most important thing is to continue to eat a healthy diet sot hat your body can replenish itself and keep on a regular cycle. If you have new symptoms or continue missing periods, then please seek a medical evaluation.