I have found that clothing sizes and fits seem to vary all over the place depending on the style and manufacturer. And I've been every size in the last 12 years from size 24 to size 8!!

Since you were given the clothes and didn't have the option of picking them out yourself for fit, then I'd say ask some sewing friends if they can alter then, or check your yellow pages for a seamstress to make the ones you have fit better.

Personally I've always found that having a looser fit feels better, and a more taylored type top elimitates that 'pregnant' look.