Hello, holly6.
You can try to check your GST/HST summary report from September 2018 until January 2019. If there are no transactions showing in this period, they might not successfully recorded in QuickBooks. You’ll need to enter these transactions so you’ll be able to remit GST. You can also create a lump sum transaction to avoid entering them individually.
Lastly, You can also check your Audit log (Gear icon>Audit log) to check if they were accidentally deleted.
Please visit us again if you have other questions.