You often can't go by the sizing on the pattern and your dress size, but once you get the pattern size right you will be able to cut out any pattern to that size, because every pattern maker uses the sam guide when making patterns. No pattern will get you a perfect fit either. They are made for the perfect body and you have to make adjustments for your body.

First you have to get your measurements correct, so make sure you are taking them right.

Consult the tutorial below for sizes. If you've never sewn for yourself before it is a good idea to make your pattern in a cheap material before you cut into the good material. Then you can make adjustments on your practice piece.

Here is a link that might be useful: Pattern sizing

Hi - looked up the pattern & it's a retro wrap dress (right?), so I imagine that it would look rather large when laid out flat.

FYI, womens apparel manufacturers can basically choose whatever measurements they want to correspond w/ their sizes - & Ready To Wear sizing has gotten really misleading over the last decade or so. I can now wear size 0 in some brands, when I used to be a solid 6 in Misses & a 9 in Juniors. I worked for a small manufacturer for awhile back in the late 80s & their sizes were determined by the clientele demographics - which tended to be bigger than average. The 'average' nowadays is even bigger & size labeling has reflected that.

Menswear(mostly) & pattern makers do not go by the same 'rules' - they tend to go by measurements, rather than a size label.

Here is a link that might be useful: Butterick B4790

Do the math. Find the pieces that They say should fit you and measure all the pieces at the path where they would go around your bust. Then add these measurements together to see if it totals close to your current measurements. if not try the next size that might fit and do the same. Remember: you are wanting the finished measurements so leave out the seam allowances when your doing the math. once you've figured out a estimated size you can use the seam allowances during the sewing process to adjust just a bit.

FYI, a pattern/garment has 'ease', that means it does not measure the same as your body - unless it's swimwear or something designed to be skintight. Depending on the style, you might find from 1-2 inches of ease added to the bust/waist/hip measurements - or more.....