Filing questions

Hi - I have an EIN for my business, but 100% of what I earn through it comes in a W-9 from the company that I contract under. I’m making a small amount from this business. My full-time job is salaried and I have considerable withholdings each month when I receive my check. I filed my personal taxes reporting the complete W-9, which of course is connected with my EIN. 1) Am I still supposed to file the business tax separately / additionally, even though that income has already been reported and taken out of my personal taxes refund? And am I supposed to be reporting business tax quarterly since it’s a commission-based income? I’m hoping to grow business, but it’s been hovering under $5000 a year in additional income.