I would say yes, you can convert your roleplay into a novel.
But it won't necessarily be easy.
If you think you'll just be able to copy and paste your written roleplay session into a single document, give it a few tweaks and hey presto, you have a novel, then I'm afraid you'll probably be disappointed.
A novel has a lot of structure that your free form roleplay will not have. This might have been different if you had a GM who had cooked up a storyline with an arc for your characters to loosely follow, but you do say you do it free form.
However, I think there's a good chance that you'll have a lot of great nuggets that would be formed into a novel - with a lot of work.
You will probably have developed some pretty good characters, had some interesting interactions and created some plot ideas.
My recommendation would be to now follow a novel writing structure, such as the Novel Writing Roadmap (https://www.novel-software.com/novelwritingroadmap - disclosure, this is my site) which will explain how to take steps to turn an idea into a premise into a plot skeleton into a full blown structure.
Once you've yanked and massaged your ideas into the structure (and you'll need to be ruthless in cutting out all the inevitable fluff and waffle) then you can get down to the business of actually writing the novel.
You may be able to use some of the sessions you've already used as first draft material, but it's likely it will still need to be redrafted several times, just like any other novel.
I hope that's helpful.