You are not an S corp. An S corp is a separate legal entity, distinct from its owner or owners. You might be the owner, or one of the owners, of the S corp, but you are not the S corp.
An S corp has to file its own tax return, Form 1120S, separate from the personal Form 1040 tax return of its owner(s). The Form 1120S return for the S corp includes a Schedule K-1 for each owner. The owner enters the information from the Schedule K-1 in his or her own personal Form 1040 tax return.
Did you (or someone else) file the Form 1120S tax returns for the S corp? Did you enter the Schedule K-1 in your personal tax return for each year? If so, it doesn't matter if you used TurboTax Self-Employed instead of TurboTax Premier. The resulting personal tax return is the same. Using TurboTax Self-Employed does not mean that you filed as self-employed. TurboTax Self-Employed can also file simpler tax returns.
If you reported all of the S corp's income and expenses on your personal Form 1040 tax return, and did not file Form 1120S tax returns for the S corp, then yes, you have to amend your tax returns. But you first have to file the Form 1120S tax returns for the S corp, so that you have the Schedule K-1s to property amend your personal returns. You should go to a local tax professional (after April 15) to help you straighten it out, and to show you how to handle the accounting and taxes for an S corp.
You cannot file a Form 1120S tax return for an S corp with TurboTax Online. You have to use TurboTax Business (which is a different product from TurboTax Home & Business). TurboTax Business is available only as software that you install from a CD or download, and it is only available for Windows, not for Mac. TurboTax Business does not prepare personal Form 1040 tax returns. You need one of the personal editions for that. The personal editions of TurboTax do not prepare Form 1120S returns for an S corp. For more information about TurboTax Business, go to the following link. However, you should probably have the tax professional prepare the Form 1120S returns for your S corp, at least until you are more familiar with it.
https://turbotax.intuit.com/small-business-taxes/
