Really, the decision to write a book should come from you. You sound like you have a story to tell, which is, if you ask me, one of the most important aspects of writing. If you feel you have a story worth telling, then tell it. It doesn't matter if you've had writing classes, many writers haven't. Writing only improves the more you do it.
If you really want to write a book, and you really want to tell your story, I say, go for it.