Is Cat still going to hollywood arts while they're baby sitting? Because if they're only 16-17 then they should be going to school

Yes she is because she mentions that "she has to go to school" or "she's back from school" and in the latest episode(in the USA) titled #new goat it says Sam and Cat are both in high school

Actually, the show said its "two College roomates" that means (im sure) cat is going to college, and Sam is going to an online college. There ages arent 16-17, its 18-19, im guessing since there in college.

yes she is still there