Congrats on fighting anorexia and beating it!
Unlike others, you are asking the right question. How to write a blog comes before creating a website, making money from it, or anything else. So, here are a couple of suggestions:
1) Start by researching what's out there already.
2) Keep a pen and notebook at your side while doing that.
3) Note what all has already been covered and to what depth.
4) While doing research, you will note lapses. Sometimes, content won't be enough. Sometimes, info will be half cooked. I think you got the drift. This will give you topics to cover that other has missed or haven't covered thoroughly.
5) Blogging is no longer limited to text. In fact, text based are slowly taking a backseat. They are being replaced by vlogs (video blogs). So, I would recommend checking Youtube for the content you want to create.
6) See what anorexia content creators are selling. See if they really have value or you can plan something people would like to pay for. It can be a PDF guide, access to video lessons, personal diet, etc.

Long story short, do your homework.

There are tons of things you can do to get blogging right. It is a crowded place but if you find a niche, then, there certainly is big money there. Trust me, I have been written blogs that sold for $400 a piece.
Here are two resources I think will help you down the line:
https://www.upreports.com/blog/build-brand-identity-online-100-tips-ideas/
https://www.upreports.com/blog/blog-optimization-growth-report-free/
Best of luck!