Just wanted to let you know I totally know where you're coming from, and I could have easily written your post!
I'm actually a comfortable size 16, but still find myself buying 18's that are too big. I can't wrap my head around the fact that I don't have to wear plus sizes anymore. I have shopped in the "regular" sizes a few times now, but I totally feel like an imposter. Maybe when I'm not in the biggest "regular" sizes (i.e., XL tops), I will feel like I have finally made the transition. Still, there is definitely a difference between a plus 1X and a regular XL (or even regular XXL...regular XXL does NOT equal plus size 2X). Same thing with plus size 18 pants and regular size 18 pants. It's so confusing!!

And yes, Cherrypie, I do expect alarms to go off! LOL! "Buzzzzzzz...too small, you're deluded.....Buzzzzz"
16 is such an awesome, but such an absolutely difficult size. You feel too big for the "normal" shops. You're not *really* big enough for the big girl places.
I remember when I went from the large end of normal clothes to the small end of plus-sized. I can't wait to have the problem of shopping both places again.