Do I have enough donor hair to cover my head?

If you are considering surgery it would be best to discuss your options with a doctor. You need to explain to your doctor your goals and expectations.  The doctor needs to examine you to give you a better assessment.
The success or results of a hair transplant surgery is not about "how many" or "the number of grafts".
The results depend on a variety of other factors such as how long you keep your hair, how you style your hair, the hair color to skin color contrast, curl of your hair, the thickness of your hair.  If you have very fine straight hair that you keep very short, a hair transplant surgery will NOT look good.
The overall success of a hair transplant surgery depends on: (1) artistic and technical skill of your doctor and team (2) communication between you and your doctor to establish a realistic goal.

This issue moving forward is going to be your crown area. You have sufficient donor hair to cover the frontal area and hairline with an FUE procedure. This should be done first, and then the donor area can be re-evaluated to see how much hair you have in reserve to attack the crown.

At a young age you need to be prudent with the treatment you decide to have. You can have a hair transplant but you will need to be realistic with your expectations as you won't be able to achieve the density you previously had before balding. A hair transplant in combination with SMP might be the best course of treatment to give you the illusion of having thick hair at the front and crown.

At a young age, you have lost a significant amount of hair and your donor area is limited.  If you haven't yet discussed finasteride (Propecia), minoxidil (Rogaine), laser therapy (LLLT) and platelet-rich plasma (PRP) with your physician you should do so and get started on a maintenance program.  You have an aggressive form of hair loss, and you need to be careful about using up your available grafts at a young age.  Once you get stable on a maintenance/prevention program you could consider a conservative hairline.  If your goal is complete, dense coverage a hair system might be your best option.

Advance stage hair loss in young age is quite challenging.
From the photos, you still have plenty of donor hair but would not be sufficient to cover all the area with good density. And thinking further about future hair loss from aging, you may loose more of your existing hair and transplanted hair.
The possible outcome that you can expect from hair surgery is the frontal and mid scalp coverage with fair density. Additional SMP session can help, illusion back up of the thickness.

The donor supply can be measured and managed and a hair transplant can be substituted with scalp micropigmentation to allow someone like you to get good results