I do not have a problem with getting items altered to fit perfectly. Hems, waist bands, sleeves are simple alterations. I prefer to have items taken in (rather than let out) and do not like altering the shoulder line of garments - as that can be trickier for dressmakers to get right. I have sensitive skin, so if something irritates my skin, then that is non-negotiable. In your situation, a migraine is so awful, I would keep well away from synthetics.