First apparel I’ve ever sewn — Wahid waistcoat

I tried to make careful measurements of myself with help of my wife, and left default fitting parameters for the Wahid project. But after careful construction, it’s clearly coming in too small around the chest. The pictures of the outer shell include a 1cm seam allowance. It’s also leaving a large, weird bulkiness in the lower back. I think the shoulder cut and upper back looks largely alright?

Can anyone recommend how to regenerate the pattern to produce a better fit? What changes on the design options would help the two problems (tightness, and bulky lower back) and/or should I increase some of the anatomical measurements I gave to my custom measurement set?

This is my pattern JSON information

{"result":"success","provider":"FreeSewing.org","type":"pattern","id":28086,"createdAt":"2025-05-21T10:16:00.052Z","data":{},"design":"wahid","img":"default-avatar","name":"Wahid / May 21, 2025 Michael Fit","notes":"--","settings":{"measurements":{"biceps":370,"chest":1070,"hpsToBust":260,"hpsToWaistBack":520,"neck":410,"shoulderToShoulder":460,"shoulderSlope":20,"waistToArmpit":260,"waistToHips":110,"hips":870,"waist":890},"units":"metric","metadata":{"setName":"michael first measurements"},"options":{"buttons":"5"},"sabool":1,"sa":10,"samm":10,"embed":false},"userId":135460,"updatedAt":"2025-05-25T06:10:11.837Z"}

I’ve never made any apparel before, so any recommendations/advice are welcomed

Here are some notes I made for myself

Here are the other views.

So far the most important amendment was to chop the length in the back. I measured where the top of my belt-line was at my back and at my side, then carved an arc out of that. It was a big chunk taken out (105mm). But it made a huge difference to the back wrinkle-mess.

I still question that the back edge should be straight, so I’m going to carve some of that out as well.