Craft/sewing stuff is hard to go through. 🙂
What I do is put all "like" items together.
When seen as a whole group of "like" items then you don't worry that you may not have enough because you can easily see that you do have more than enough.
This way you can see all duplicates too.
With duplicates I keep the best and toss/donate the rest.
One important question to ask yourself is
"will I really ever do this project?"
Being honest with yourself you may decide there are better things you would rather do with your time.
Our tastes change over time too.
Colors/styles/patterns that we used to prefer may have changed.
Let go of the past and enjoy the "new" you.
Just because something is nice is no reason to keep it if you can't think of any way that you would ever use it.
Decide how much you can properly store and keep pulling out things to toss/donate until your keep pile is the right size for the space.
Keep all the very best and let go of the rest.
Hope I have answered your question.
If not then keep asking me and will keep trying to.
Sincerely, Tillie 🙂