Kickstarter.com? Have a charity to give the book away for free, donate all proceeds to charity intended, get name of book out there. Than word of mouth will happen if its deemed in favor. Even throw up the option of 'If yo udont want to participate in charity and still interested in book, it is available on amazon.. bla bla bla.'
Just an idea. Word of mouth is the most successful tool. Even throw your charity up on reddit if you like for more attention for a supporting cause.
pure opinion because i have no experience in this but - you already have your name out as much as you probably can other than making friends and encouraging them. try writing another story. if its liked well enough people may look to find other stories written by you. i do it all the time with authors i like. I don;t know if its practical for you or not but - give it a go.
Unfortunately, yeah, you need to spend a TON of time 'advertising' your book if you're not actually paying for advertising. Sign up to some online forums that deal in creative writing/fantasy writing. Start sending free copies of it to reviewers maybe?