((hug)) Even though you listed 6 things, I would think that the emotionally intense youth group might be also because of your youth group leader graduating? Does that mean she is moving back home or getting a better job?
Also, You school being a drag and your "C" grades... are centered on the same thing, right? Being an average student is nothing to frown about!... You can turn things around your senior year, but it will take work, and maybe tutors! However, you will still have 2 years of basic college to do well, and then go for the university you want.
As for the incident with your friend, it ended ok... but your depression is making you only focus on the bad part. What happened is the way life goes, hopefully...that things will turn out ok
Now, for not being able to see your therapist... how often do you generally go? With Monday holidays, there are many patients that don't get to see their T on particular weeks.
I hope you don't crawl into a hole at all. I think your efforts to distract yourself from your negative thoughts is a good thing, good self care! Now, work on those things you can change, and move on from those you can't.