Hi Sebastian,
It is so great that you are in tune with your body and want to explore and understand what it tells you and what it may need to support you. Your feelings and observations are just that.......nothing you should feel shame about. You are obviously a proactive young person. I wonder if you have talked with you doctor about the stiffness and tightness in your body. You mentioned anxiety. One of the things that I noticed when I am anxious is that my body tightens and being in that state for an extended period can make my body sore. You said you are meditating and that is so useful for depression and anxiety. I wonder if a yoga or tai chi practice might be useful . Something gentle but useful for you and your body. Give yourself some pats on the back for being so aware. When I was your age....and I am 77 now..... I was completely out of touch with my body and feelings.