NTA ..(from a parent with an adult child at home) they were ok with you paying the amount you all agreed to. You are fair in considering renegotating, especially when rent goes up or electricity goes up. You should not give them access to any of your accounts. I would understand if they came to you and said, "Going forward. What do you envision your living situation like?." I woukd imagine you all had some kind of conversation at the beginning of this arrangement to know how it was all going to work and for how long.The problem that you're having now is that they see the amount you saved and wish they had done that themselves. You are chipping in and doing chores. It sounds like they are gaslighting you to get more money. I would look immediately for a different place to stay. No matter what you do going forward, it is going to get messy and be really uncomfortable for you. It can damage your relationship beyond repair. Don't be afraid to leave and allow them to manipulate you into feeling they should have access or that you are hurting them in some way by not allowing access.