Sorry to hear of this.
As a manic-depressive myself, I'm wondering, were you ever under the care of a sychiatrist?
The reason I am asking is this:
I went to psychiatrists for 20 years, off and on, and would complain of depression. They would diagnosis me as depressive.
I was mania-depressive, but they would never inquire about a possible manic side, by asking, "Well, do you ever stay up until 2 a.m. in the morning?" and "Does you mind every race from idea to idea for hours?"
Finally, after 20 years, I was given Lithium for mania, which also knocked out my panic attacks. Why 20 years?
The Lithium, which lowers mania and lessens depression, goes along with my anti-depressant.
Ok, you've answered the question in the second sentence of your original post. You said:
"I have suffered from depression for the past 20 years. Recently I was diagnosed with bipolar when I had a severe manic attack which lasted 3 months"
You were on an anti-depressant for 20 years, and they never asked once in those 100's of sessions. "Do you ever stay up until 2 the in morning, or having racing thoughts?"
For 20 years, they never mentioned the word "Lithium?" Never mentioned the word "mania?"
That could have been prevented.