Is this normal for 3 months and 3 weeks post-op with 4200 grafts? I have some patchy area. (photos)

It may take 8-12 months before seeing the final results of your hair transplant surgery. If you are concerned with the density and shape, follow up with your surgeon for an exam.

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.

Some people grow hair sooner than others. The average person wouldn't have seen any growth at this point. Give it more time and your results should get better and better.