I want to improve my relationship with my father

Hi im 21 years old and I ve been feeling anxiety for a long time because of the relationship I have with my father. I went to a psichologist for 2 months and found out that probably the reason of my anxiety was caused by a fear I feel around my father. My father doesn't physically harrass me and i never felt that I feared him at all, but the way I talked to him, how I acted around him and how I avoided being around him unconsciously we the reason I considered that maybe I do fear him. So, as any other problem i have with a person, I talked to him about it and he just noded and listened to me, trying to understand what might be causing this. My father in some aspects is a really reasonable guy yet so radical minded about some others. Even if he seemed really concerned about this problem he wont consider asisting to therapy or talking anyone about it, he even told me to never tell him again to do so cause he felt it to be an insult (he thinks psichologists are only meant for mental illness) So never told him to do so again but even after talking several times about this matter the situation was the same as always, nothing changed, even specific situations we talked about like knocking my door before entering my room or trying to talk on a lower tone would just stay the same the next day. Im mentally tired of this, I can't focus when studying or rest on my free time because I don't see any improvement. I respect many things from my father, but I cant stand arguing about anything whenever we talk or having to follow his rules even if im 21 and have no reason to do so, still I dont want him to be mad so I try to fullfil most of them. I dont know what should I do, I dont want to leave home because i would make my brothers and mother sad if I do so, but I feel every week i feel this pressure is making me more and more sad and stressed. I have no bigger problems, at the moment im a full time student and im trying my best to learn the most out of my carreer but I feel frustrated because i cant focus as much as i would like to, Sorry if its hard to read or if I had misspelled anything, english is not my first language but i try to improve.