According to the Fair Work Act (section 536), pay slips have to be provided to an employee within 1 working day of payday, even if an employee is on leave. Details of the information that should be included on your payslip are here.
Once you obtain your payslip, you should be able to determine if you are being underpaid.
If you have been underpaid the Fair Work Ombudsman advises that this “needs to be fixed as soon as possible”.
You should follow up with the practice manager and/or your supervisor to resolve this as soon as possible. Your RLO can also support you with this.