why is my balance zero?
There’s some explanation of this.
If you not see the balance from Brave users contributions, mean the received BAT not yet sent to your publishers wallet. Each contribution from users not directly sent to publishers wallet, but to escrow wallet first.
If you asked about balance from referral, I see that you have 7 confirmed referral, it simply because Brave not yet process it too. Some information can be found here Issue with confirmed Referals
Hope that can help. Let me know if you another question/s.