I also use the Baby Centre and What to Expect App on my phone. It's really helpful and interesting to learn how your baby is doing each week.
I think I only really started showing around 20 weeks. Before that I was waiting eagerly for my belly to grow instead of looking like I just gained weight. Heheheh.
|20 Weeks - Baby is as big as this banana|
|25 Weeks - You can see the veins quite clearly.|
|25 Weeks - No stretch marks yet but that horizontal dark line. And my belly button is getting more shallow.|