Confusion about college choices...?

[Elle]

I'm a 15 year old girl. Since I was tiny I have wanted to be an author and when I went to look around college I was going to choose a 'print based media' course. This led me into everything writing such as journalism, photography and other writing jobs.
Recently I have been wanting to go off on something completely different feeling that I'm not good enough and that it would bore me. So now I have chosen 'health and social care' course and have been looking into working in mental health care etc. I have been so so excited and think I have made the right choice, and I've been accepted!
However tonight I was filling out a hopes and dreams sheet for homework and realised that writing is what I love to do, and can only really see myself doing that. I feel so sad and scared about the future and have no idea what to do. I would like to go into mental health care but when I try to imagine myself doing that I just can't, whereas when I try to imagine myself behind a computer or with pen and paper I can.
I just don't know what to do, please someone help me