Ahh I know what your mean, except I never had kids, lol. So I don't have a decent excuse for my belly XD
Anyway Here are some tips I've found-
Undergarments are a girls best friend!
seriously, find a good shapewear, it will smooth everything out and even bring you down a size. The one I've found and love has a build in (strapless) push up bra, and then goes all the way down to mid thigh. So I don't need to wear a slip or bra, just my shapewear.
Shape of the dress is key!
if you want to hide you tummy, make sure your dress has a shape, if its a straight dress on a curvy body the dress will hug your curves, and probably not in the way you wanted. So pick a dress that narrows in at the smallest part of you torso. And then flairs out at the waist.
Distract they "eye"!
Even though you don't think you have a big chest, fake it. Get a push up bra, or one that just looks really great on you. Then choose a dress with a V-neck. (if you feel the V is a little too deep, just use a safety pin on the inside to bring it up an inch) By showing off with a V-neck your elongating the neck and making drawing the attention away from your middle.
Even if it isn't big bling, make sure to wear a necklace, earrings, bracelets. Necklaces and earrings help with the idea of bring the "eye" up, just like the V-neck. Plus if you have cute jewelry more people with be looking at that, then your curves.
Show some skin!
If your like me might not like showing off you arms, but I am fine with my legs, so I always wear a short formal jacket with my dresses. But I make sure to get a dress that ends right around my knees. Because I'm really short, having a shorter dress and showing off my legs actually makes me look taller, along with wearing heels ;) But if you don't like your legs, and feel comfortable with your arms, pick a longer dress that's a halter top or sleeveless.
Phew, lol Those are the biggest things I can think of :D I hope that helps you a bit!