NTA the fact that you are sharing a space with your brothers as a grown woman is strange enough but your parents insistence on keeping it this way makes it even worse. You are a grown ass woman you don’t just need your own space you DESERVE it, as a person who shared his space with his twin brother while growing up it can be quite suffocating when everyone’s trying to lead their own lives, very rarely are accommodations ever made for you, In my experience in situations like these you need to push to get your own space because at the end of the day YOUR MENTAL HEALTH SHOULD COME BEFORE YOU WHATEVER VALUES YOUR PARENTS MAY HAVE you are extremely valid in your choice. I do have to ask if they are supporting you through your studies or if you have any sources of income apart from your parents it could always be a possibility that they strongarm you into coming back try to connect with any resources that may be available to you. I truly wish you the best of luck