I had the same experience with Party of One: The Loner's Manifesto by Anneli Rufus. Basically the entire book is devoted to letting you know that it's okay to prefer being alone (which is NOT the same as being lonely). There's a section in which the author states that some people enjoy dating, even if it's not "the one," because they like the company. Loners see that as a waste of time and would rather just be with someone meaningful or be on their own. I thought, "Woah, that's me! There are other people like me? It's okay to be like that? Awesome!"

If I don't get enough time to myself per week I go a little nuts.

Lots of titles come to mind, for different stage of my life.

One of the most recent ones is "The Art of Falling in Love" based on Zen Buddhist philosophy. Helped me slow down, take stock and refocus on living life one moment at a time.

And "The Far Pavilions" . I read it once a year for about 5 years straight. It would take me a good month to read it (normally I can whip through a novel in a few hours). This one is an epic story that illustrates the meaning of true love. If I was stranded alone on a desert island, I would want this book with me.