I’m contemplating a boob job. What size should I get if I do it?
What size are you currently?
It's totally subjective, and up to you, of course.
I think many cosmetic surgeons recommend that patients wear these "cutlet" things (which are essentially fake boobs) in a bra to get a sense of what it's like to have a larger sized breast. Maybe you could try something like that to see what it's like and see how they look on you.