I Have Let My Hair Grow Out 3 Months and the Back of My Head Looks like It Is Balding

You have significant donor site depletion. This problem is caused by over-harvesting the grafts from your FUE three months earlier. The only thing you can do is to get Scalp MicroPigmentation, which will hide the balding spots, but it will not add hair.

See here: https://scalpmicropigmentation.com/scar-covering/