Also, you say your doc says it may happen. I understand the loss of sleep and please forgive me if this offends you, but is this a specialist or a regualr MD? Are they doing everything they can to prevent it being needed? (Having gone through a bit in the past year, I found I have one kidney which was "stunted" from birth, so basically function with only one, so have had some experience with nephrologists. The one I have here is fantastic.)
Secondly, to get some sleep and not worry too much, I highly recommend Qi Gong Flow for Beginners as a positive focus and calming thing to do. It really helps to stop the worry cycle of the mind.
Good thoughts coming your way. Take some deep breaths and blow out all that worry!