Depression Support Group
Depression is a real and debilitating condition that is often misunderstood by family and friends. Its meaning can range from a prolonged period of sadness to an actual mental illness with specific symptoms. Find and share experiences with others who are going through the same struggles.
I'm way past 16, but I do have memories of it, and I know that getting up the courage to talk to your parents can be very difficult. One thing you can do is tell your parents that you would like to get a complete physical. You have the right to ask your mom to NOT be in the room for it. Then you can tell your doctor some of what is going on; she/he may then refer you to a therapist for an evaluation.
This is a very important step; putting it off means that these problems you are talking about (crying a lot, sleeping a lot or not at all, eating everything in sight or not eating at all, etc) can get worse and then get to the point where they are issues you have trouble dealing with.