Hi GerganaK,
Welcome to Apple Support Communities. Make sure that you have Reminders enabled for your accounts. As mentioned in Set up Reminders accounts on iPhone - Apple Support, do the following to enable iCloud Reminders.
Add your reminders stored in iCloud
Go to Settings > [your name] > iCloud, then turn on Reminders.
Your reminders stored in iCloud—and any changes you make to them—appear on your iPhone, iPad, iPod touch, Apple Watch, and Mac where you’re signed in with the same Apple ID.
Then, take the following steps to add other accounts.
Add other Reminders accounts
You can use the Reminders app to manage your reminders from other accounts, such as Microsoft Exchange, Google, and Yahoo.
1. Go to Settings > Reminders > Accounts > Add Account.
2. Do any of the following:
• Choose an account provider, then sign in to your account.
• If your account provider isn’t listed, tap Other, tap Add CalDAV Account, then enter your server and account information.
Once you have those accounts, you should then see all accounts from the Default List page shown in your screenshot.
Have a great day!