Weight gain is different for everyone hun. I put on 3st with my son in total, that took a while to lose! I started off 9stone, after I had him I was just shy of 12 stone.
This pregnancy I've LOST 1stone 9lbs

but my boobies have gone from 34E/F to 36H!!
If you're worried change what you're eating/cut down on portions and try to exercise more. There are specail pregnancy exercise DVD's or even just look on the internet.
But like I said, everyone is different xx