Is it normal to gain weight while taking Zoloft?

I had a baby five months ago and started taking Zoloft two months after that. My doctor said it is the safest to take while breast feeding. I lost all my baby weight plus some before taking Zoloft. After a few weeks of taking this I noticed weight gain. Went back to the doctor and gain 9 lbs in 6 wks. Then went back 4 wks later and gained 5 lbs. Needless to say my doctor decided that we should wean off the zoloft. My question is will i lose this weight now? And is it normal to gain weight like that with Zoloft. I know with breast feeding i should be losing also. Anyone have any input on this?

Thank you!