It is not muscle gain.

When we exercise we do so to
retain muscle, not to gain it. Sorry, just want to be up front. It could be a lot of water weight due to exercise, stress and salt, but not 16 pounds worth. It does sound like you are putting an awful lot of stress on yourself and it is quite interesting that you have lost inches through this.
I would suggest sticking with the exercise and focus heavily on the diet. You need to get sodium out of your diet whenever possible. You didn't tell us what your diet looks like, but you may consider switching to whole foods so you know what's in them. Even deli meat packs in the sodium! Canned soup is notoriously bad as is ham and pork and if I'm not mistaken, diet sodas. Read a lot of labels and get rid of the salt. Drink a lot of water to flush this stuff out of your system.
Are you journaling? I don't ask this lightly!

I do not journal and I do not feel it is necessary. But if I had two weeks to fit into a dress I'd already purchased, I'd journal every bite. I've read that you should journal it
before anything goes in your mouth, not after. That sounds like good advice to me.
In the meantime, you might venture out to the stores and have fun trying on pretty yellow dresses just so you're not stressed out over where to find one. Then you could either purchase it with the intention of returning it or ask them to hold it for you. If it was me, that would take the pressure off.
And this may sound silly, but practice some deep breathing throughout the day. Again, it's about the stress.
Heck, put yourself through a two week boot camp and then come back and tell us how you did.

I'd love to hear.