How do you know if you have damaged grafts?

It is best to contact your surgeon for post surgery issues and care since all doctors have slightly different instructions. Your surgeon knows the specifics of your surgery and can best assess your recipient area.

Thank you for your question and photos
the number of grafts a patient will need depends on the thickness of their hair and the extent of their hair loss, which can be determined by the Norwood Scale below.
During a hair transplant, grafts are usually removed from the ‘donor area’ located on the back of the scalp and relocated to a balding area. The back of the scalp makes a good extraction area due to the high volume of hair follicles that congregate within that region that are not affected by the balding process. Specialist surgeons will remove a small amount of tissue that can grow hair and relocate it to the desired area of the head without damaging them.

You are doing the right thing to wash your hair gently, remember don't pour shampoo directly into the transplant area, do not grab it vigorously, don't scratch the hair in the transplant area to prevent hair from falling out.