It also sounds as though you are effectively blaming yourself for not making new friends. It may not be your fault. You describe yourself as “boring” for a lack of partying but I would not have made that characterization. Not wanting to party is typically a sign of maturity. It may be that you simply have different interests than those with whom you currently associate; it will likely not always be that way.
A significant concern about your depression is that it has hurt you occupationally. You stated that you can’t keep a job because of your depression. That is clear evidence of how depression is degrading the quality of your life.
It’s encouraging that you are resuming therapy. In therapy, it will be important to analyze your social skills, your fears about approaching others, and what is the root of your depression. It’s unclear from your letter if your depression is caused by your current situation or some other factor.
You should also consider medication to help improve your mood. Medication works best in tandem with psychotherapy. If you’re willing to engage in treatment, then you should expect a successful therapeutic outcome. Please take care.