I am a big fan of Ann Taylor, AND they have size 2 clothing.
Here is the closest store to Milwaukee, go try some things on
Mayfair Mall
2500 N. Mayfair Road
Wauwatosa, WI 53226
(414) 774-9222
*minor hijack* I hate when invitations say "Black Tie Optional". It is either black tie, or it isn't, just tell us so we KNOW what to wear.