Hi Alice,
If your Raynauds is very severe and you have difficulty doing everyday tasks and it is impacting your life severely, you should talk to your parents about seeing if there are any services you can get to make writing and other tasks easier. There are computer programs you can get where you can speak to your computer, as an example, if you find typing to be difficult. Also, I am unsure if you get help through your school, or if you are home schooled but if you go to school and are struggling to write, you could see what support your school could offer.
I also found
this website that has a lot of helpful info you might find useful. They also may be able to let you know if Raynauds can be classifyed as a disability.
Hopefully this helps.