Only you can answer that question for your own situation. Did the fawns look like they were old/large enough to survive on their own? I think I would have went ahead and shot her if it looked like the fawns could have survived. If not then I would have done what you did and at least give the fawns a chance. By it being on your mind I can see you still have a concern for the doe and her condition. That is a good thing.