Just make sure this is discussed well ahead of time with gym, parents, and especially host family. Your parents would have to pay the gym directly somehow (automatic credit card debit maybe?) and your host family will need to be willing to transport you to practices. If you plan to compete, you may even need to discuss things like, are there other gym parents or coaches who may be willing to take you with them to some of the meets. Your host family may well want to accompany you to some meets, but teams in the US may compete a lot more often than what you're used to. Getting kids to all those meets is a big commitment even when they're your OWN kids! If you can find a flexible gym and a super-supportive host family, it could be an awesome experience, for you and for your US teammates!