[Ennui.]

Yeah, I'd say this is okay. Both of you are basically around the same age, so it's not like there is a huge age difference, and as long as both of you are on the same page with the relationship and what you want and don't want to do, I don't see a problem with it. Make sure that you two are honest and communicate with each other, so that way the relationship stays strong and any problems and concerns can be discussed right away. That will also help the relationship to last and continue going well, such as through high school. Obviously I can't guarantee anything, but there's always a chance.

There is also no set age to determine your sexuality, which means that yes, you can know! Some people have known their sexuality since their early childhood, and others are older before they find out. Either of these situations are fine. It's a gut feeling you have, and you know how you feel and who you like. That is fine! It's completely normal that you know your sexuality now. It's also okay if it changes later on, and it's okay if it doesn't. No two people experience it the same.

Best of luck!