I have not had ECT, but I am a huge Carrie Fisher fan, and she talked about her ECT treatment in her memoirs "Wishful Drinking" and "Shockaholic."
In a nutshell, she described ECT as "blowing the cement out of her brain" and was a very effective treatment. The major downside she described was memory loss, and a smaller downside was having to take a full day off for treatment as it apparently takes a lot out of you.
I have heard from others as well that if you have run out of options re: therapy and psychiatry, it is a really recommended treatment. I of course cannot speak for that as I have not experienced it myself.
No matter what you decide, I hope you are well and are able to heal