Trust issues

Whenever I start a sweater, I always wonder if it will actually fir when it is done. I can't trust myself to knit to a gauge or decide on the right size needles for the yarn. So before I started Sunrise, I looked at the KAL. Apparently there have been some sizing issues. Do I make the 37" or 41"? Normally, I would be a 38-40". There is overlap but is that included in the chest measurement? Why do I overthink so much? There is a chart for adding width to the back but adding more math to a project doesn't work well for me.

I knit a gauge swatch and have to go up a needle size to get gauge. I have started the sleeve but am second guessing myself about the needle size and the sweater size. (I chose the 41".) Worse case, I knit to the shoulder and realize it is too big and frog it. In the grand scheme of things, it isn't really that bad.