I can really relate. I’m a native English speaker and a pretty fluent French speaker. French is my fourth language, but my best non-native language.
I’m quite comfortable speaking it, but writing in it well seriously intimidates me, to the point where I’m reluctant to try.
I think part of the problem is that in French, the spoken and written languages differ a fair bit.
I can think fine in French when having a conversation, but when it comes to writing, it’s harder, because the more flowery phrasings and extra verb tenses of literary French sound unnatural to me.
Even after years of reading French literature!
At least with written English, there’s less formal difference from spoken English.
That’s still a challenge, however, for there are subtle differences in expectations.
They may even be harder to spot because they’re so slight and seemingly unimportant.
Reading and practice are the keys to the kingdom, of course.
They seem to have worked for you. You write beautifully!