Is it wrong that I'm mad at my gf for cancelling a vacation?
I'm sorry your vacation was canceled? Is it because you wanted to go away?
No, it's because she wanted to save money now and I am ready to spend it on the vacation.
Well you could just go anyways and then watch what you are spending. That way you are both respecting each other's wishes.
I just don't want to see my money going to waste.
It's important to compromise with your girlfriend about what you both want. Maybe you can change the vacation destination to a less expensive place. You can also push the vacation back one or two weeks and get a couple of gigs for extra money.