FUE transplant 4400 grafts 3 days p.o. Most doctors advised me 3700. What are your opinions about density? (photos)

If you are concerned please follow up with your doctor for an exam.
You will have hair loss after surgery. You may have graft loss after surgery. Not all the grafts will take. You won't really know until you see results in 6 to 12 months.

At this point you need to sit back and see how things look when the hair in your donor area grows back and the grafts grow.  

3500 is a huge amount for one session, let alone anything higher than that. It's way too early to know what the results will look like but that many grafts poses a risk for over harvesting. At this point all there is to do is wait and see what the growth looks like in the future.

Great question. It is very difficult for me to give you an answer after 3 days PO. You need 12-15 months for full hair growth after the surgery for a correct evaluation and results. I will suggest you to keep your follow-ups with your hair surgeon. Good luck.

Your doctor appears to have gone out of the permanent zone, into your neck hair which is not permanent and above the permanent zone on the right side.