Hi Anniina, we have a number of hemp and nettle fabrics on our site at http://www.source4style.com. We are a B2B online marketplace that allows designers to source more sustainable materials (and eventually services) from a curated network of global suppliers. Let us know if you find what you're looking for. You can order swatches, sampling or production yardage - just look for the minimums for each product.
Please check out my website www.barkha.com. I have numerous nettle and hemp fabrics listed there and have added a lot more to my portfolio since the website was made. Please email me and let me know what your requirements are.