Hello again @Bona,
you havre to submit an application for national regulaisation of your stay ("Antrag auf Legalisierung") to your local immigration office here in Germany. You stay woll then be permitted until borders reopen and you can travel back. It is important to do this before your three months of visa-free stay expire.
I hope my answers were helpful and I’ll be very pleased if you contact me again with further questions. I'm a member of the mbeon-staff and I‘ll be glad to guide over a longer period of time. mbeon is an online advisory service for migrants via the mbeon-app, which you can download on your smartphone for free. You'll find me in the mbeon-app under my name „München, Frau Müller“ and get confidential one-to-one advice in a safe virtual room where nobody can read messages. For further information please visit www.mbeon.de.
Download for Android: https://play.google.com/store/apps/details?id=de.zone35.mbeon
Download for iOS: https://apps.apple.com/de/app/mbeon-messengerberatung/id1408795643