Despite whatever delusions you may have about having a Heidi Klum-esque body post-baby... you are mistaken!
Your tummy will NOT be pretty. Envision Jello with a layer of skin over top. Awesome. Pregnancy is basically the anti-liposuction for your stomach... like someone took fat and injected it under your, previously taught, skin.
When I'm standing, you can barely notice a difference (mind you, I "ain't" wearing the tight t's that I used to either)... but sit me down and you could get lost in there right now.
On the plus, after 15-20 weeks of being a giant person (first 20 weeks of preggers doesn't count), you're still gonna feel skinny as hell! ha ha ha, so enjoy it! :)