What my core is: "my nucleus" has remained the same. My atmosphere of experience has forged and polished me. I have always explored creativity. I am an HSP (high sensing) and an empath.
"What is my 'why' for writing": I have so much I want to say and share. I need to share my experience. As you say it is therapeutic.
"who is my audience": It depends on who reads and connects with me and also who I connect with. I have found sweet, heart warming and encouraging connection with others within shared experiences.
"I chose Medium": my daughter always sends me articles to read. Eventually I became a member to read more articles. Months after that I dared to hit the publish button on something I wrote. I love the connections with people and their work. This experience has expanded my mind, boundaries and my life.
Welcome to Medium WS, it's a great adventure!