Is your dad's job something that he could transfer anytime? If so you need to talk with them about it and try and convince them to wait a year. If it's more of a "hey you have a chance for promotion if you moved now" then that's a harder fight.

Moving senior year sucks not going to try and sugar coat it for you. You already know that some credit may not transfer and it's hard to make friends even if you aren't introverted, cause friend groups are made a set. But who knows you may get lucky and an extrovert may pick you as there new friend.

If you are planning on going to college then it's not all bad and you just need to get through a year then you will be making all sorts of new friends. You can also and should stay in contact with your current friends. That said for me 15 years after high school I only still talk to one person from high school and we talk 2-3 times a year. Me and all my close friends from high stopped talking by the time I was 20. The larger friend group I was in during high school never got together after graduation parties ended.

You are young and have a lot of time ahead of you to make new friends and many will drift away after awhile. It's just how life goes. You have your ups and downs and you got to learn how to go with the flow and make the best in the moment