Can Lithium do more harm than good?

I've been taking 1200mg daily for about 13 years but I still have severe emotional problems every day. I feel like all I can't let any of my frustration out and there's this eerie calm that's out of place.Once you've been on it a few years, most P-Docs are afraid to take you off it. Lithium has this reputation of being so trusted and benign, but I think it interferes with my natural abilites and leaves me at a disadvantage. What do you guys think; can you tell when Lithium is not working or did you have a bad experience from it? I'm especially interested to hear from anyone else who's been on it 10+ years. Thanks!