I'm now 7 months post op. Really disappointed with the density of the transplant. I had 1500 grafts (Photo)

It's a hard thing to gauge without seeing any before pics, but in general at 7 months it's definitely possible you'll see a little more improvement. Generally patients shouldn't worry about their progress (barring zero growth or incredibly patchy growth) until close to 9 or 10 months. While I doubt you'll see a huge improvement, you may see some differences by then. 
If you're still unhappy definitely talk to your doctor- there are some other options that may help improve density or even a second transplant could be a potential solution for you.

It looks like the transplants grew but if you have fine hair, a second hair transplant could have been predicted but based upon these photos, it will be needed anyway. More length will help.  I always tell my patients that a second transplant may be needed if there is not enough fullness present, something almost always the case in people with fine hair.