How do you report hours that vary week to week? after 16 years as a pharmacy technician

I work some days through a staffing agency while still certifying. Any experience at all would help. Sometimes my paycheck is late by a week. Did anyone get an overpayment notice from a mistake?

Thanks for writing this out. I went through something close to it last year, and it got easier once I kept a simple log of every call and form.