Learning German and Having Trouble with Native Speakers?!?

I know I'm only young(I'm fifteen) and have been studying german for little over a year,but in class I can understand my teacher quite well,(she is austrian) and on listening tapes I can keep up.I am working at the highest level class for my age group.But when I was on holiday I met some germans,and introduced myself,feeling confident,and they spoke so quickly,I had to ask them to slow down at least twice,and felt so rubbish.I thought I was good at german,but when I got around native speakers I forgot what to say and basically went quiet.It's really frustrating me! Has anyone had similar problems? I want to just be able to have a normal conversation,but I get so nervous I forget everything i've learnt.

Suggestion:

You expect far too much after only one year of learning a foreign language. Native speakers have a much more extensive vocabulary than you have. We use words that you haven't even learned so far, we speak in colloquial language and some dialect, we often don't pronounce our words as clear as a German teacher would do, and of course, we speak much faster than you're used to.

But believe me, we have the same problems when it comes to other languages. For example, when I watch an American movie or a sitcom in English, I also have trouble to understand everything. They either speak too fast or too inarticulate or they use vocabulary, slang-terms or wordplays that I just don't understand. Well, of course it also depends on the actors, but then again it's really frustrating when I notice that I only understand half a sentence, even though I've studied English for so many years.

Oh, and by the way, it's absolutely normal that you get nervous and forget what you've learned when you stand in front of a native speaker. It's like taking a test. I think everyone would feel the same. Anyway, keep smiling and don't give up!