Dear @JaneMir,
Welcome to the Wefugees Community and thank you for reaching out to us.
Unfortunately, I am not a tax expert. I am afraid that you may have to get support by a so-called "Steuerberater" (tax consultant or accountant). I was making some research to find out if you can ask a "Lohnsteuerhilfeverein" (income tax help association) for help. But as far as I read, they are only allowed to provide counselling for employees and not for self-employed people. Nevertheless, you could still contact an association in your city to be sure (using this search engine).
In any case, please also don't hesitate to get back to us with any further questions.
All the best,
Meike