Did you use the Online version? That's common to end up with multiple accounts. First LOG OUT of whatever TurboTax account you're logged into right now. Then use this TurboTax account recovery website to get a list of user ID's for an email address. Run the tool against any email addresses you may have used
https://myturbotax.intuit.com/account-recovery/
If you used the Desktop CD/Download program then the only copy is on your computer and not saved or stored online.
OR are you in the Desktop program? Go to File-Open and see what files show up. If you used the Mac Desktop program it should still be there. Did you make any backups?
How to find tax files on Mac
https://ttlc.intuit.com/community/tax-data-file/help/find-your-tax-data-file-in-mac/00/26206
