Tihom,
Give it some more time. I am sure you will be pleased in a few more months. I had a HT by Rahal 6 years ago and I remember going through the same thing as you. It took quite a while to see good results. I remember shaving my head the past 6-8 months post surgery until I saw the new hairs finally grow. It took about 8-9 months when I let my hair grow out and I have been very pleased ever since. I should also let you know that I had 3200 grafts for my temple and hairline area. Your 3400 grafts were placed in a much larger area than mine. This might be why you are not seeing a fuller crown. It might take another procedure, concentrating strictly in one region to yield the results you are looking for.
I am planning on getting a HT with Dr Radha for my crown area as I am seeing slight thinning (with age). I have been doing my searching and found good reviews about Radha but my only concern is the long travel from the US. I was very pleased with Dr Rahal however the cost is almost 3 times as much. Once I go through with the procedure I will follow up on this forum with my results.
In closing, the one thing that I come to realize is that HT is not a miracle solution to hair loss. We will never get back the hair we once had. Keep that in mind.
