The best way I can answer and help you is this.
1) relax and take a few breaths you don't need to work yourself up.
2) take time and talk with the native people in the Netherlands. That will help you by immersing yourself in the language. It's probably the fastest way to learn the language without a class. (kind of what you do with your first language)
3) Ask if you can see what is going to be on your language test. If you can, practice speaking and hearing what is on it. If not, just practice as above, but know how to make things negative, past, present, future, formal and informal, etc.
4) If you have a friend in the Netherlands, ask them to help you out.
5) If you still don't feel at least 85% better about the test, ask to hold off on it for another month so you can make sure you pass, and you can go to the college.
6) Also read and watch the t.v shows/movies without subtitles in the language. See what you know in each sentence and what you don't know. Great practice and it shows you what you know and don't know. (I am learning Japanese and I do this all the time, I think it helps me learn a little faster than a lot of my classmates.). :)
I am sorry if this isn't the kind of answer you are looking for, but I know just talk with people and learn from them. The reason, you can't learn an entire language over night. I know you have been studying and that's awesome, but immersion with practice is the only "fast" way..