Make sure you're being honest with your teachers and parents about it. If you need to repeat a year who cares, especially if you skipped half a year because of the different school schedules between disparate countries.... besides, you'll be the cool older kid in the class (just wait til yr 12!).
Anyone who tells you that it's not ok isn't looking out for you. School literally exists for your future. Make sure you use it to your advantage... I didn't, I pushed myself as hard as I could because it was how I got my validation, and I'm a complete mess as an adult as a direct result. The amount of bullying and trauma I received as a result of the social disconnection was insane, and it's forever affected my outlook on life.
Be in charge when you can be. <3