Littlebean, you are still very young with a lot of things to come including changes that will be good. I agree with the poster who said “fake it until you make it”. I go to work with a smile on my face even when I have just finished crying about something and usually I actually feel better a little later. Maybe a counselor could help you sort this out if you feel like you are so depressed that you cannot fully function. Being sad is one thing but when depression inserts itself into your life enough to affect your school, work or relationships negatively then it could be time for some outside help. There are counselors out there who work on a sliding scale basis, so hopefully you can see someone even if you do not have health insurance to cover it. The most important thing is to be kind to yourself, life is a marathon not a sprint and this difficult time will at some point become your past.
PS-you might be interested in my reply to wellwisher on this thread.