Welcome to our forum.
I think OKC should be helpful to you in finding people. No guarantees on whether you will have to do a little traveling to meet up with someone, however.
On this site we have a Dating & Friendships subforum
, you can look there if you haven't already done so. Also you could google "Washington polyamory" and see what turns up in the way of poly groups.
I wish you the best in your search. With time and patience, I imagine you'll meet someone eventually.
Glad you're here,