I'm so sorry that you're coming up on another birthday but faced with the same feelings of sadness and depression. I know you said you missed your appointment because of illness. Have you thought of seeing your therapist twice a week until your birthday passes? Sometimes those extra sessions gives a person a bit more strength to get through those periods of increased difficulty. Hopefully you've considered medication even if only temporarily.
My dad and I were talking a few days ago and he voiced his amazement at people that are often mad or dismissive of others struggling with mental illness. He said something to the effect of: if a person who is struggling with physical illness is encouraged, comforted and helped then why is mental illness any different. It's not... too bad your family doesn't realize that. It may be hurtful to you but they are causing as much damage to themselves and they don't even kow it.

Hoping things will be brighter soon...