Heya, I am also on Sertraline (as well as Mirtazapine).
I've been on 200mg daily for coming up to 2 years now, and it hasn't caused any psychological problems or negative side effects. The only difficult side effect I did get was a very dry mouth initially (to the point where I couldn't swallow), and that was easily sorted by reducing the dose and increasing it back up more slowly (I was in hospital at the time so meds were all closely monitored).
It won't be right for everyone, but it is very very very unlikely to cause any psychological problems, and if there are side effects that you aren't comfortable with you can speak to your doctor and either get the dosage changed or try a different medication.