I've seen many cycles succeed with one egg and just one embryo. I don't know the odds, and of course the chances are better with more, but try to keep your spirits up and look at the bright side. Your chances are much better with that one embryo than without it...
I am in the same situation as you, this is my second IVF - 1st resulted in a m/c - I didnt seem to respond as well this time around could be the new and improved protocall my RE had me do but I had 8 fertilize and only 1 transfered on day 2 they graded it a C which I would say is a three on a scale of 1-5. Not feeling very hopeful here either. Please know that you are not alone.