I second the person who mentioned how different their belly looked w/ #2. With #1, I didn't really "show" until almost 7 months. I was in a wedding at 5 months and looked chubby but not pregnant.
This time, I showed as soon as we conceived. I am 19 weeks and feel like I did at the end of the pregnancy last time.
I too had 10 pounds extra with #2 so that certainly contributed. When I'm done with this one, I will be working extra hard to get back to pre-pregnancy weight. I'm tired of being fat!