City Hall Dress

Looking for a dress for March City Hall. I am a size 12/ 14 & finding that most websites don’t have dresses big enough for me. Examples: websites such as Reformation, Outnet etc It’s really bumming me out. The one I really wanted from Anthro I got in a size 16 and it was SO tiny. I’m so incredibly frustrated. What are these wedding sizing? The proportions are crazy small? This was supposed to make me happy not sad! Where do you go for a dress if you are not plus but not tiny???