Wanting some advice on college please :)

I just graduated HS and I’m wanting to go to school to be a diagnostic medical sonographer. If anyone here is in that field, can you please tell me about your journey? I know an associates degree is 2 years and you have to do prerequisites. My question is, do those prerequisites count towards the 2 years or is it time added on to 2 years? I have a tour with the college soon but was just wondering. Thank you very much. I am very nervous and feel like I’m too dumb for college but I really want to do this to make myself and my mom proud. I would be the first in my family to go to college.