Sir Douglas Bader was a bilateral amputee with trans tibial on one side and trans femoral on the other as far as I'm aware, and he flew operational flights in WW2. I'm sure there will be other pilots who are amputees as well.
I would think that passing the class one which is the standard medical requirements would show that your fit to fly. I've been trying to get mine for the past year because of past medical history so I'm sure if they thought there was an issue they would certainly let you know about it.
I agree with amanda, prostheses these days can be quite cosmetic depending on the types of socket/ suspension methods and most people would be hard pushed to spot that you are wearing one whether that's in sitting or in gait pattern.
I wish you well for the future, I think you should go for it.
