When you write your Master, tell him how disappointing it has been to not have been shared with other Black Alphas for you to satisfy and to take care of you while he is away. IMHO, It was his responsibility to make sure your needs would be satisfied, especially if he appreciated you satisfying him! We all know that he has a piece (or three) while inside, and will until he gets out (if ever).
I suggest you attempt try finding a new Alpha, even a temporary one, starting where you found him. And, make sure he'll be willing to share you with others, so if something happens, you won't be without, and you can be that good white slut you really want to be, with an Alpha/Master who will be more appreciative of your skills & obedience.
You deserve it.