Final Dress Fitting?

My wedding is in 3 weeks and I went to 2 fittings already. One was to try it on and hem the 2nd was to do the bustle. The 3rd is to just go in, try on the dress and make sure the bustle is right.

I made my last appointment for 3 days before my wedding. I am worried I will lose some weight and then the dress be a little big and them not being able to fix it in time.

When did other's get their last try on/take home fitting?I do have a corset back so it can be pulled tighter but of course I am stressing..

Thoughts???