You've had a kid already, so your body is jumping into "let's EXPAND THIS UTERUS!" mode. I started showing way, way faster with baby#2. A visible bump at 5-6 weeks, in maternity pants by 8 weeks.
I am seven weeks and this is my second. The bloat is crazy. I seem pretty normal in the morning, but the second I eat something, my stomach is huge. I have been wearing a jacket at work when the bloat is bad.
I feel less bloated with #2. My work best friend keeps asking when I am going to out myself. I keep telling when I start to show which isn't anytime soon. My pants are just starting to get tight at 12 weeks.