I don’t care what anybody tells you, do all the measurements you want. The size you think you are is always and will always be wrong.
Here’s the thing, having a Bachelors Degree in Fashion design and working the industry for over 10 years has taught me that the size chart is different for every company you shop with. The higher end brands love Vanity sizing (which is calling a large a small to make the customer feel better) and the lower end brands are usually closer to the average size chart but even those aren’t always correct. A lot of company’s have there own version of a size 6 and you really have to look at each individual companies size chart to figure out what size you are “according to them”
For my brand I love either making clothing that is stretchy so your in a range of small, medium, 2x or what have you. But I also like when you just send me your exact measurements so you get a piece that fits you and your body. It’s honestly not that hard to do, I tell my clients all my USA clients who aren’t in Philadelphia to just go to your local dry cleaners/tailor to do your measurements (you can see the measurements guide on my site) and they always find one close by. Another issue with buying clothing from stores or online stores is when your not an average size all over from bust to hip, your dress/outfit will fit great in one place and not look good in another.
Long story short, always look at the size chart first and see what size you fit for them. Or you could always order Monica Monique custom!