To Of Course (and everyone else):
IMHO, It comes down to whether you think being a shadchan is a business or you are doing it for the mitzvah and to make two people happy.
If you did it for the mitzvah and to make to people happy, then you should not be harping on the money. The couple, plus their parents, should have at least professed their gratitude, and given you a token (whatever it may be, even money) to show their appreciation. However, since you ARE harping on the money, I am assuming you meant to actually make money for your time and effort.
If you are doing it as a business (even as a money making hobby), then I agree with Wolf that you should have at least specified your intentions orally in the beginning (written would have beem a lot better). Since it seems you did not, then the burden of proof should be upon you to prove that you meant it as a money making opportunity and not gratis.
On a personal side note, after reading all these posts about wanting and demanding money (in as much as considering stalking the chosson and kallah during their sheva berachos on facebook!) for what I consider a huge mitzvah, I am very glad I decided to not deal with shadchanim for my dating life.