I am sixteen years old, and I had unprotected sex about two weeks ago. Since then I have been experienceing head aches, more frequent peeing, tiredness, dizzyness, nausea once or twice, and had a little brown discharge earlier today. I don't know if this is all in my head because I know it's a possibility, or if I really am pregnant. I been scared before by having a late period, but never been scared before even missing my period. Its too early to take a home pregnancy test, so I didn't know what else to do.

It could be possible... But like you said it's hard to tell this early. This two weeks is when you should have had your period? Or 2 weeks is when it should start up? It could just be late... I hope so!
There are more accurate home pregnancy tests nowadays though, but if you don't want to spend money on a whole pack you could go to your nearest youth clinic (google "youth clinic" or "sexual health clinic" in your hometown to find the nearest) for a free test... When I was 17 I had the same problem, I went to them shaking and scared and told them I might be pregnant, they were very kind and caring about it. I took a test from them and they told me the news... suffice to say they help you out. If you are they ask you what you want to do and show you all your options, set up any schedules and all that... They can also hook you up with free or very cheap birth control!
Though I'm reading over your symptoms and it all could be from anxiety too over waiting for your period to start. If it's full on vomiting nausea... it might be more serious but I'm not sure it starts as early as two weeks, I was under the impression it's within the 2nd month that happens. Either way, hang in there! Hope for the best, if it turns out you are you do have options and you can always find support from us here!

You likely would get an accurate result on a pregnancy test since it was two weeks ago. Are you due for a period soon?
Either try a test now or wait until when your period would be due and see what happens at that time.