Hello, RachelIllsley. 

I understand your frustration entirely, and It's crucial to keep accurate records in the system. QuickBooks Online and QuickBooks Desktop are completely different platforms. Although you can export your 7-year data, due to limitations, some information may be missing depending on the size of your company file.  

For additional information about importing data from QBDT to QBO, please refer to this article: Learn about converting from QuickBooks Desktop to QuickBooks Online.  

I've also attached an article discussing what to expect when converting files from QBDT to QBO: Switch from QuickBooks Desktop to QuickBooks Online when you know what data doesn't convert when you migrate from QBDT to QBO.

Moreover, you can check out this article: QuickBooks Desktop is being discontinued. It will also help you move your data to QuickBooks Online or download your data to move out of QBDT. 

Feel me in if you need additional help. I'll be here to help you out. Have a great day!