Question if amended return necessary

You shouldn't amend your return. You can either download blank estimated tax payment forms from the IRS and manually enter the amount you pay each quarter or you can use IRS direct pay without any forms: https://www.irs.gov/payments/direct-pay

You can pay the first two quarters at the same time by July 15, 2020.

Amending is not required ... to compute the estimates you can ... follow these instructions: 

To access your current year online tax returns sign onto the TurboTax website with the userID you used to create the account - https://myturbotax.intuit.com/

Scroll down to the bottom of the screen and Click on Add a state

This will take you back to the 2019 online tax return.  If you have filed the 2019 tax return do Not make any changes to the return that was filed.  Only access the estimated tax section and then print the estimated tax forms if needed.

1. With your tax return open, enter 1040-es in the Search box located in the upper right of the program screen.  Click on Jump to 1040-es
2. Answer No to the question,  Do you want to change your W-4 withholdings for 2020?
3. On the next screen, Review Your Estimates, select Review Now.
4. Proceed through the interview, answering questions about your 2020 filing status, income, deductions, etc.
5. Eventually, you'll come to the Print Vouchers screen; answer Yes and we'll include your 2020 1040-ES payment vouchers when you print a copy of your return later.