*hugs*
sometimes... we hurt ourselves. life, the human experience of being alive, is all about what we decide to sacrifice and what our sacrifices give us. I learned that self harm sacrifices so much for absolutely nothing. Now i have a scar on my arm that's actually larger than the cut I gave myself, and it's a reminder that SH has never done anything for me but take.
If I have been asking you to try and be happier when you're really this sad inside, and it makes you feel guilty for being ingenuine, i apologize. if you are depressed, it's okay to act sad around other people. by all means, try to conquer your depression, don't just lay down and die, but don't hurt yourself even more because you have to pretend to be happy.
I'm glad you're seeing a therapist, and I know it's difficult that they won't be able to meet with you when you need them to. It's not your fault.
You are loved. You are redeemable. Your life isn't nearly over, and the things you have done, to yourself, to others, can be forgiven. They can be forgotten. I promise you, you're going to make it through this.