Quoting Katrina Plantz:" i have the same due date as you sep 16th. and im pregnant with baby number 2. i have a baby bump already. ... [snip!] ... you look up prgnancy models and look at 5 weeks there are alot of them that are already showing so dont wory your self to much."
You are NOT showing, its bloat.
To whoever said you show sooner after you have had a baby, thats not true either. With my oldest daughter, I showed around 16 weeks, and with my youngest, I didn't show until I was 23 weeks.
When I was pregnant with my second child I didn't show at 5 weeks,I am sure it's just bloating