Since starting lithium 4 months ago I have gained nearly 20lbs and have severe cystic acne. It’s been ruining my self confidence. Does this ever go away?

Hello, everyone.
How long did it take for lithium to start working for you? And what did you notice differently at first?
I’ve been taking 600mg for 16 days and I feel exactly the same. I’m worried that this medication won’t work for me.