Heart, even if you were eating the same as before pregnancy I think you will find that you still put on weight. Our bodies are programmed to slow down our digestion so we can extract all the goodness and build up a fat storage for breastfeeding.
As long as you eat when you feel like it and don't deprive yourself you should be fine.
The 25lb thing is more a guide and more as a maximum healthy weight gain rather than a target you have to achieve.
As for sleeping on your side, even though I mostly do I spend a lot of time on my back (no, not for that! naughty girls...), too. So I asked my midwife about it. Her advice was to stay comfortable. She said that once the baby starts pressing down on lungs etc. (later on) I would feel uncomfortable and automatically seek out a different position.
Right now, ducky is just past my belly button and my breathing is normal so I'm still ok, I think.
I hope you don't mind me saying that I love this thread and how successful it is! So many of us made it to second tri and beyond!
I guess all of our medical cocktails have something to do with it. When I was in a first tri due month thread last year the loss rate (mainly unmedicated first pregnancies) was much higher...