There is no such thing as sustainable fabric
The entire industry talks about "sustainable clothing production". That doesn't exist. Period. No matter what material your clothes are made of, they have a serious negative effect on the environment.
So what can we do?
What if we freed ourselves from the thought that we need new things all the time? Is it really that important? Why do we "have" to buy new t-shirts every summer? Wouldn't life be much easier if we had a few we loved year after year? And if the company you bought the garments from offered a lifetime service with free repairs, free of charge?
We're just asking the questions. You have the answers. What we do know is that the only way to reach true sustainability is to reduce the consumption.