Since you are filing on a Schedule C, for a Single Member LLC, as a disregarded entity, you do not need to enter your capital contributions (which are considered your equity) on the tax return, so you do not need to amend.
The tax return schedule only reports income and expenses and not your capital contributions.
It is a good idea, however, to keep a balance sheet for your business also (outside of TurboTax.) A Balance Sheet would include assets, liabilities, and your equity. Quickbooks is an great tool to use to do this!