micheleh: Is there a setting that I need to change?
It sounds like the Transaction History timing is set too low for your estimates. By default we only reach back 31 days into your transaction history, longer than this and you'll need to adjust your default settings.
Go to the tab Quickbooks > Synchronize, scroll down to the transaction history section and click the Show options per transaction type link. Scroll down the Estimate drop down and change the default to a date range that works for you. Click Save Settings, then click the Sync Now button at the top for a full sync.
~C