I gave up sewing my own clothing years ago. It was such an exercise in frustration: I would cut the pattern size out that my measurements indicated I was, sew the garment and put it on… and it didn’t fit. The shoulder seams would slop off, underbust seams wouldn’t fit under the bust, and the whole thing would sit wrong.
Here’s what I didn’t know – the measurements on patterns are a lie. According to Simplicity, I am a perfect size 20. But if I make a size 20, it doesn’t fit correctly, because I do not have a B-cup. If you are more than a B-cup, you should use your upper bust measurement, not your full bust. In truth, I am a 16 at the shoulders, not a 20. I will need to add fullness at the bustline (and ONLY the bust area), however, to get a shirt to fit. Typically, I also like a little less ease at the waist and more at the hips, so this reduces my waist to an 18 and my hips to 22.
I didn’t learn this until I took a sewing class – this would be my first sewing class in 15 years. I wish I had known this little gem years ago – I would have had a closet full of awesome clothes that I made instead of a pile of scrap fabrics.