My best advice is to figure out what level of expenses you are comfortable maintaining for an extended period of time. Put together an Excel sheet of all of the things you will spend money on monthly, also budgeting an extra hundred for "fun" things, and for "unforeseen expenses" as well.
From a mindset perspective, I would suggest you pivot your view from "being responsible" as a negative thing, to a positive- "taking charge or taking control of all aspects of your life" which just means that you are entering the next phase of life! Becoming a more self-sufficient person who doesn't have to rely on anyone else.
Hope that helps.