I am worrying a lot about my donor area: it appears thin overharvested and red. (Photos)

4000 FUE harvesting may well cause donor area depletion unless you have an above average donor density.You wont be able to tell until your scalp heals over the next several months.

Hello
According to your pictures, you should contact the doctor who did your surgery.

You can do frequently massage (circular way) on the donor area with disinfected hands. This massage is helpful for blood circulation.

Also, you can use healing antibacterial ointment.

Over harvesting results in moth eaten appearance and can damage existing healthy hair follicles. Approximately 2,000 follicular units is what can safely be removed in one follicular unit excision harvesting from the safe donor area. Hopefully some of the thinning is due to shock loss and improves over time.

Few people can safely support a 4000 FUE graft transplant without developing a see-through donor area