If you have successfully filed your returns in the past you would have received a NetFile confirmation number each time one was filed. Also, you would have received a Notice of Assessment by mail for each year to show you if you were getting a refund or if you owed, and if you qualified for any credits. This would have been sent to your home address which was listed on your income tax return.
If your uncle has completed your returns please ask him to sign in to his account to look for your returns and be sure they were all successfully filed. He may also have a copy saved to his computer.