Welcome to our forum!
It is great to have you aboard, I hope you enjoy your stay here, I'm sure you will. We have so much to read and learn! Have a look around on our various threads, and post any thoughts or questions you have.
Ethical Slut is a good book; you might also want to take a peek at Opening Up (by Tristan Taormino). Not that Polyamory.com won't give you enough study material alone ...
Are you planning to take on any additional partners, or pretty content as-is? I find myself pretty comfortable as a "leg of a V."
Good to have you with us.