You got some good advice above, I think starting with the school counselor is a great idea. If you do have depression, and I agree it sounds like it, that is a good first step to getting some help.

The symptoms you describe are very typical of my experience of depression. I have had some of my worst experiences when things were going "fine" in life. For me it is a chemical imbalance and I need medication for my brain to function more normally and for me to be able to function in the world. I used to think of it differently, but now I have come to understand that depression is an illness like any other. It is a medical condition, not a flaw. I'm so glad you are here and shared what you did. I, too, hope you will keep us posted about how you are doing.