In my 20s and 30s I suffered greatly from severe depression. I felt like I was at the bottom of a deep, dark well surrounded by darkness. I was suicidal and at times, so withdrawn that I could not communicate with anyone.
After several tries (years) of various anti-depressants and bio-feedback therapy. I learned to "act happy and be happy" through cognitive behavioral therapy.
I am now in my 60s and no longer have deep depression, but I do still have mild depression. I don't take anti-depressants anymore, and I don't feel the need to.
The only advice I can give is - don't give up! There is a medicine or a therapy out there that will work for you as an individual.
It takes a long time and a lot of determination to overcome depression, but it can be done. Just don't give up.