I have had it. I was scared too, but when I got to the point where I was that depressed, it saved my life. I have had series of 12 before, gee, that was years ago, but I was always on medication after. The memory loss was disturbing, I used to write things down for a few days beforehand. It was mostly short term memory loss that upset me. Once I knew what to expect it wasn't as bad. I had always journalled a lot so I could refer back to that if I forgot something. I didn't take any visitors while I was having the treatments, it was just easier and I stayed calmer, partly because I didn't have to worry about saying anything I might regret or forget later. It depends what works for you.
You didn't say if you were on medication after the ECT or if it was supposed to do everything for you? As I said, I was on medication and continued counselling for quite a while after that. I hope this is of some help, all I can share is my personal experience.
I am not on medication now, it is years later and I think I do okay! 8o)
Take care,
J