Is my donor area over-harvested? Can this be fixed by placing grafts into the bald patches? (photos)

The only way to tell is to wait about 2-3 months.  But in general, your donor zone looks very depleted and looks like there is a possibility it may be permanent.  Unfortunately this is the risk taken with FUE, especially when it is done by an unqualified clinic/doctor.  Fixing this by transplanting grafts into the depleted areas is possible but extremely difficult and labor intensive.  In the last year I have started to correct a lot of procedures such as yours by transplanting grafts into the depleted donor zone with hair taken from the beard or chest as well as micro pigmentation.  I would recommend finding a skilled surgeon in your area that could help you.

It will be very difficult to answer this question at this point. 
I would start immediate treatments with Laser Cap to try and get all the hair back into the growth phase as quickly as possible.
Sometimes when an area is over harvested it can create shock loss all over.
Have you let your Doc know the concerns you are having? If not, I would start there and see if they can assist with treatment.

It may or may not be patchy when it heals. Only time will tell. You cannot tell with photos alone.3500 graft FUE is considered a very high number of grafts harvested at one time.  It may lead to patchy looking donor area when you keep your hair buzz cut.  It may even out with time and longer hair.

First
of all I think that you have to wait because 10 days is a very short period.
There is a possibility that you will have more hair to the donor area in the
future. In case you don’t see any improvement, theoretically you could do hair
transplantation to the donor area but the problem is where the grafts will be
taken from. Probably, there are some areas which could help as donor areas but I
don’t think they will be enough for resolving completely your problem. Probably
you might start considering of micro pigmentation. Anyway don’t be pessimistic
and wait for 4-5 months until you see the final result and then you can decide.

Below are two critical questions that you need answers to before moving forward with an FUE clinic.  1) Is your Doctor the person doing the FUE harvesting or is a Physician Assistant or technician doing the harvesting? 2) How long has your surgeon been doing FUE and FUE harvesting?  

Its very difficult to say at this stage as its only 10 days post surgery and to speculate how it will look in 3,6,9 & even 12 months isn't possible, so for now focus on looking after the new grafts and making sure they grow well in the recipient area and should, in several months time, your donor area look thin then you may want to look at SMP to simply colour this area an give the appearance of density as more HT's wouldn't be a path I would advise.

At 10 days you can't tell if the area has been over harvested or not. Generally removing 12-15 % of the donor area leaves behind reasonable density. You'll know if 4 months if too many grafts were removed or not. No, transplanting hair back into the is not a practical option. SMP is an option but I understand this is not what you are looking for. 

Here are some things to consider when considering an FUE hair transplant:1. Finding a skilled surgeon that can extract a significant number of grafts while not wasting donor hair is very important. Technician clinics that use unlicenced technicians for FUE should be avoided.2. Extracting very high number of grafts such as more than 3000 can cause prolonged healing and camouflage time while risking donor depletion. It also leaves little donor hair behind for future sessions. The decision should be made carefully.3. 3500 grafts is a significant number and even if it was done by a skilled surgeon, prolonged healing and camouflage time is expected. There may also be some shock loss due to this that usually resolves in 4 months.4. If the extractions were not done professionally, then permanent donor depletion is a risk which will prevent any future attempts for repair and improvement.

At 10 days after FUE harvesting you would usually expect to have sufficient hair coverage to hide the donor sites completely and for the donor area to blend completely and uniformly with the surrounding hair. This does not appear to be the case from your photos. It is possible that you have experienced shock loss in the donor area. If this is the case, then you may have to wait 3-4 months for the hair to start to grow.If, at 6 months, the hair has not recovered then you should see your surgeon for assessment.It is unlikely that hair transplantation to the donor area would be a viable option. After all, where would the new donor hair come from?If things don't recover one option might be to have micropigmentation tattooing.

one of the risk factors associated with FUE technique specially in larger sessions is hair depletion or thinning in the donor area. This should have been discussed with you before you had done the procedure.