There is great variability in depression. Some people will respond very well to antidepressant medication. Other people will improve their depression after psychotherapy. Still others will need a combination of both.

Yes, there are many biological treatments. While you are waiting for antidepressants to work, start physical exercise.

Absolutely yes, with therapy , medications, regular follow up

Depression is a brain disease. In order to treat it there should be an evaluation by a trained provider who can assess the nature of the illness and then determine what treatment is warranted. 70% of depressions will respond to first line treatments. The other thirty percent are considered Treatment Resistant and 70% of these will respond to either TMS, TBS or Ketamine Infusions. Begin with a thorough diagnostic evaluation by a Board Certified Psychiatrist

Depression is a complicated problem. Usually there are situational stresses and often cognitive and behavioral processes that have self-defeating components. There may also be biologic components. I would suggest a comprehensive evaluation by a psychiatrist you believe listens well and can relate deeply to your situation.

Take a look at this link - it should be helpful.
https://www.sharecare.com/health/depression-treatment/article/recovering-from-major-depressive-disorder