Weight Gain/ Working Out While Pregnant

Ladies- Where have you gained your weight/ how much have you gained so far?
I have never been a fan of working out since I've always had a fast metabolism and haven't really needed to. But my metabolism has slowed down and so far I've gained 20lbs which I'm not really bothered by since the only places I've noticeably (to myself) gained are in my upper arms, thighs and hips. Anyone know anything about starting to do pregnancy safe exercises at this stage of pregnancy? These are the only areas I want to tone.