Oh phooey!! Since I cannot send you a private message, I will just go ahead and post to the forum. What could it hurt?
I really do not like to be the bearer of bad news, and I hope I am wrong, but that discharge could be a sign of a uterine infection. If that is the case it would be the reason why the doe, even though she was living with the buck, is not pregnant. If the infection is serious, that doe may not ever breed again. Please understand that I am not saying that this is the case, but it is something to consider.
Meanwhile you might check into what you have to do to file a claim in Small Claims Court. To sum it up: you bought a doe guaranteed to be pregnant, she is not pregnant, and she may not breed again. One other thing. Is the person you bought the goat from a member of the American Dairy Goat Association (ADGA)? If she is, if necessary, I can help you file a complaint if it comes to that. I am not a big wheel in ADGA but I know people who are.