I had treatment of ECT that consisted of 12 session in a month. I was also medication resistant. It was the best treatment i have used yet. It has been 18 months and i am so much better. I am constantly improving, i don't even rate on a K10 anymore. I still take anti-D's and a mood stabiliser but these keep me stable rather than treat an existing depression. I did have some memory issues but they were only related to the time surrounding the treatment and a few weeks before. They could have been related to how depressed i was rather than the treatment. I was severly depressed with some psychotic symptoms.
How age effects effectiveness, or side effects is not some thing I know about, maybe you could get a second opinion. I am 35 rather than 16.
Yes it was scary but it got easier to tolerate with each session. I had a mad headache/migraine after the first one but by the last one i returned to the ward ready for lunch. (I tolerate anesthetic really well).
Hope you find a med that helps first, but i would do it again if necessary (touch wood).
Hope this is helpful.
PM me if you have any questions?