IMPROVE YOUR WRITING IN A FOREIGN LANGUAGE
The first thing I would do is to make writing in a foreign language more natural. Of all the skills it is probably the one you do less and you can’t improve on something without practicing it.
Your speech has only improved when you have started having more conversations. Your listening is probably better when you were watching TV in a foreign language or you had to talk to locals who spoke quickly. And it is the same for writing, it is necessary to practice it.
To do this, I would start keeping a journal every day about what you did. It doesn’t have to be pages and long pages, it could just be a short paragraph if it’s more realistic for you. But it would be a good way to practice writing, and make it a more natural skill for you.
If you have a native friend you could ask them to read it and give you some advice (as long as it’s not private) or visit this site and ask for help from professionals.
Hello Talk is an app that has some similarities with italki, as you can find people who learn your language and practice with them. But rather than organizing language exchanges with Skype, it’s more commonly used to find people in your area to start messaging and then meet with them if you wish.
I used Hello talk when I was learning French to chat with the locals and discovered that my French sound was more natural.
On the app there are functions to highlight the mistakes made by people and correct them. Some people don’t like to correct others and prefer to chat, but I found that many people were happy to tell me how I could look more natural and stress when I made a mistake.
Seeing things written also helped me not to make those mistakes while I spoke.