Operation Bridesmaid Dress!

3ish years ago in my size 20 bridesmaid dress

So... I found out this weekend that I am going to be a bridesmaid sometime this summer!  Though it was not part of the plan, a couple of the other bridesmaids and I ended up trying on dresses on Saturday.  I had no idea what size to try on, and started with a 16... TOO BIG!  I tried on many dresses over the next hour, and for a lot of them, I needed the 12!  WHAT!?  The last wedding I was in was a few years ago, and my dress (from the same place) was a size 20.  I still have that dress, and can't wait until I can hang them up side by side and take a picture.  They didn't have the size 14 for the dress that we're pretty sure I will be wearing, so I tried on a 12.  It's way too tight... I don't have to order the dress until the end of February, so my goal is to see just how much I can lose by then.  I really really want to be able to buy that 12 and look amazing in it at this wedding.  I know the bride is the shining star, but my hubby will be there, and he'll be looking at me. ;)  hehe

First step of Operation Bridesmaid Dress is a change in eating... I am beginning the South Beach Diet TODAY! (¡oy!) I've tried this before, but never really stuck with it.  I'm gonna do my best to really do it this time!  If nothing less, hopefully it will break me of my carb addiction (man, I love snacks!).  I am also signed up for a training class at the gym (I'll get into that in a little more detail soon) every day this week, and I want to run at least a mile every time I go the gym (either before or after the class).  

Any other advice on fitting into bridesmaid dresses is more than welcome. ;)