If you alraedy use a 7.5, then go all the way to a 9m sail, 8.5 a bit too close. F133 will take a 9, it's 77 wide.
Not sure about the fins, if you got a 48 with your F133, try your new big sail with it first. Then buy bigger and/or more powerfull fin if you need it.
Btw welcome back