Hi there.

I've had ECT done before and it was after many meds were tried. I was in the hospital and had hit rock bottom. I had trouble eating, showering, getting dressed, the basics. The one way I knew I had hit rock bottom was that I stopped chewing my nails. I've been chewing them since I was a little kid, but I was so depressed I couldn't be bothered. That being said, the chewing began once I started to feel better. :P
So for ECT, I would definitely recommend it as a last resort, but it couldn't hurt to bring up the possibility to a psychiatrist and see what they think.
Did it work? Absolutely. It worked better than any medication I've ever been on. However, it's not something that I wanted in the long-term. The memory side effects are bad (there are memories to this day that I'll never get back thanks to ECT treatments), and it can be harder to concentrate on things like reading. That being said, the side effects were totally worth it, in exchange for getting out of rock bottom.
I will be honest with you - it can be a scary procedure if you don't like that sort of thing. I cried more than once before the anesthetic put me to sleep, holding the nurse's hand for comfort as I lost consciousness. It's not pleasant, but neither is depression.
You'll need to talk to a psych to weigh the pros and cons. I'm not sure how it works where you are, but I had to get approval from two different psychiatrists before getting the go-ahead, and I was shown an educational video so I knew what I was getting into.
If you do decide to get ECT, I recommend unilateral treatment instead of bilateral; the memory loss isn't as bad if they only zap one side of your head.
I hope you find a treatment option that works for you, good luck!