Bettsi, You are in luck right now because empire and other apple-friendly clothes are right in style!
Your dress is very flattering and you could just cut it a smidge bigger.
Also you want things that suggest a waist but don't actually go in too far. That's why empire is perfect for you.
Another style I think would look great on you is: http://www.mccallpattern.com/item/M5536.htm?tab=tops_vests&page=1
you could even extend the tank to dresslength. I think that would be so cute.
Now for some don't's...Don't wear a top or dress that is gathered unless it has something to suggest a waist, either an empire or some other detail...if you do you'll jut look preggers.
Also straight skirts should be pegged in a little at the bottom, that will make them look more straight and cut the volumn of fabric down.
Acording to the McCalls website you should be wearing an 18...don't worry about the number it is prolly lots bigger then you wear in RTW...that's just how patterns are
Now take all this advice with a grain of salt...it's just that I'm becoming more and more of an apple after a life time of being an hour-glass...and this is what I've learned.
ps - tried to get the img to show but I don't know how, so put the link to the webpage in.