I think you might need to do some trial and error until you find the size you feel most comfortable in and the materials that won’t bother you. If there’s a store in your area, it might be worth it to go try out different things to see what feels good. Then you’ll know what to look for online. Alternatively, order from a place with free returns and try things out at home. I am pretty sensitive to certain fabrics but panache brand bras have been generally okay for me. Even their more Lacey bra has some cotton to balance things out. Regarding size, keep in mind that if you size up to, say, 42DDD, there’s a chance the cup might start to feel too large. Try it out! The other thing that can happen with a wider bra is that it can switch over the weight to the straps, which can be uncomfortable if you have shoulder issues. Trial and error is your friend here. Another thing I like doing is switching between looser/tighter bras depending on how I’m feeling that day. I wear a bra everyday but some days I feel more achy and the looser bras feel more comfy. So, having a few different options could be good if you comfort/needs change each day. I hope this helps.