Medium is really a great place to practice and you have the freedom to write about any topic. You'll eventually get used to people reading your articles, and it won't be as scary, lol.
I've done other work in the past, but I started writing about seven years ago and it took me over a year to make a full-time income. Right now, I work with 4-5 clients each month. Most of them are marketing agencies, so I usually write about a variety of topics.
I also used to post articles on Constant Content and make decent sales for years, but it's not been the same since AI became more widespread.
Finding clients is often the most difficult part of freelancing, but it gets easier once you get established. It used to be really easy to sign up at a few writing platforms to get experience, but most of them are much slower because AI has really hurt that market.
Your best bet is to try to work with clients directly or look for marketing agencies in need of medical/health writers.
Also, sorry for the long post...I just had my morning coffee!