I've run bubble hash a few times so will try and help if I can.
You ask what you are doing wrong, but I don't actually see any problem with your results. You will naturally get variation in the colours and texture and "behaviour" of the hash you get, even from the same plant, because of the many variables at play.
For example, even off the same plant, you will get parts with very different trichomes on. Some will have matured to amber, some may still be almost clear. Some will have larger heads that break off easily, others will be slender. I could go on.
Furthermore, the amount of time you stir, the vigour with which you stir, the way the matter was broken up, the amount of ice, the water temp, etc etc.
So - first and foremost, understand that 100% consistency is extremely hard to achieve. What you want to concentrate on is getting a good enough yield and high enough quality - and establishing what balance you want between the two.
You can achieve a more consistent product simply by blending. If you blend the finest two grades from 3 runs, then the finest two grades from another 3 runs (each of fresh material I mean), you are more likely to end up with two similar blocks of hash.
Finally, to answer your question about drying, I have tried a few different methods and found this to be the best: smear it onto a standard porcelain dinner plate over to one side, then tilting the plate slightly so water runs off the hash down the plate towards the other end. Dries your hash very quickly without losing anything. Very easy to scrape off the plate.
Enjoy your hash, I'm jealous as I won't be able to make any for several months!