Small melt down about my weight

So I just looked up dress sizes for the first time. I have never done that before and have always just gone by trying clothes on and the S M L sizes, which is always different depending on the brand or where you're shopping. Sometimes I'm a M and some times I can be a XXXL. I have to try them on because I never know, sometimes it's even the same brand.

So I measure myself and according to the charts I'm a dress 16 in bust and hips, but a 20 in the waist. I didn't even know they went up that high! Everyones always talking about being a size 2 or 4! I'm kind of appalled! I have image issues already but just seeing those numbers... I feel depressed.