You are describing a hypothetical and imaginary scenario in the past. As it is impossible for you to go back in the past to take your own life, the sentence should be written as a third conditional sentence. A common structure for forming third conditional sentences is:
If .... had / had not + verb (past participle form), .... would have / would not have + verb (past participle form)....
"If I had been *found dead, no one would have been surprised."
*The word "convinced" sounds off in your sentence, as it means that someone did something to make you believe their view or opinion. Therefore, I changed it to "found" and hope I have not changed your intended meaning.
On a personal note, I have friends who are diagnosed with conditions such as bipolar disorder, so I sincerely hope that you will get better soon.