Is there a way to rate your book? I want to say it's PG13 but I don't know if that means anything to self publish for YA.
when you self publish to amazon you can select an age rating on the upload screen - I right adult so i usually just select 18 plus... off the top of my head i don't think the rating is available on kobo, ibooks etc You could also put something in the blurb - but its best to stick will appeal to ages xx and up... rather than using terms like PG which don't translate well across national boundaries
I think you're probably safe with YA since it means young adult. I would call that a PG13 rating. The last YA book I read was The Fault in Our Stars. I don't read too much YA, but that's a great book. When it was turned into a movie I believe it had a PG13 rating. Although the book was better than the movie, which is often the case, I think both the YA and PG13 rating was appropriate for that story. So, I think you would be safe calling the book YA for attracting the right audience and readership.
No there isn't, and no it doesn't mean anything. That's a film classification system and meets specific criteria regarding content, and is assigned by a governing body. So unless you're an official governing body, your rating is completely meaningless. ( and even if there were a classification system for books, you would not be allowed to give your own rating. Just like you can't give yourself a driver's license.) It's best just to classify the market genre, like YA, Lit Fic etc.