Sounds like you should be in good shape. On the odd chance that you do end up with a positive blood test just talk to the doctor and explain how long you've been clean and that it was edibles not smoke.
Here in Washington the legislature finally passed a law that organ transplants can not be stopped because of a positive test for cannabis. All the medical cannabis states should be passing that same law.
I wish you luck on your transplant. I tried to donat a lung to my brother before he died but he didn't want to put me through it. I've never smoked tobacco and now I'm retired so I could easily have lived off of one lung.