Hello and welcome sister Sirius to the website,
Let me first of all congradulate you on your initiative; as feeling the need to search for the true purpose of life and the true way of fulfilling this purpose is indeed a sign of a vibrant soul. Please allow me to suggest a few steps that I think will help you in your quest, God willing.
1. The various avenues open for learning should not be taken as alternatives, rather they should be considered complimentary to one another. Learning involves getting information, observing, interacting and experiencing. These when taken in parallel provide strong stimuli for the mind, the heart and the soul.
2. Getting access to Islamic literature and reading it with an open heart should cover the "information" part. The "observing" part might nicely be covered by visiting Muslim communities in your area, perhaps someone in the neighbourhood or, better yet, visiting a Muslim community center in your area (like a Mosque). You have already begun your journey in the "interacting" world by joining this forum, you may have a more real-life interaction, again, by contactng an Islamic center in Seattle. These centers mostly entertain visitors and can also provide you an interaction-buddy (a Sister in your case) who might take you into the "experiencing" avenue by spending time with you and giving you a feel of how the Islamic tenents and ways bring peace and harmony in life.
Sorry for the long message, and sorry for not adding any specific links about Islamic centers etc. in your area, and I hope that you will find some of this useful. I am sure we can provide you a detailed list of books, e-resources and Islamic community centers in your area, so please do not hesitate to ask for any of these.
May you shine ever brighter (I believe "Sirius" is the brightest star in the night sky?)
your brother