I'm 5'6" and I'm a pretty skinny guy but my shoulders aren't scrawny. They're not bony and they have enough structure and width to make me look less skinny. My waist is a 30 and my chest measures to be about 36-37. However, when I try on 36 and 38 off the rack suits, the cloth bunches up in the back under the collar. Somewhere in between the top parts of my shoulder blades, it looks like the fabric is pulling. When I try on a 40 slim, the tension is gone and the fabric lays flat on my back. However, there's so much excess fabric in my waist area that I don't know if the suit will still look okay after taking all that fabric out. What should I do?
If what I'm saying isn't making sense, look at this video:
pause it at 0:40 and notice how the cloth right under his collar is wrinkled.