I originally used credit karma tax because it was free and I unknowingly didn't file the right forms. So now the IRS was an amended filing so that I file the correct form of the 1120s, instead of schedule C and amend the 1040 form so the income loss is placed in the correct column for the tax year.
If you did not use TurboTax to prepare your 2016 return, it is possible to amend the return using TurboTax but it will really be a pain. It would be better to use the software or service used to file originally. In your situation--you should probably seek local paid tax help.
In order to use TurboTax to amend your 2018 return, you need to purchase the desktop software for 2018 and re-create the return EXACTLY as it appeared when it was filed with the IRS/states. Every line has to be the same. Then you have to "trick" the software into thinking you filed by saying you will mail the return. (but do not mail it) AFTER that, you use the software to prepare a Form 1040X, which has to be printed, signed and mailed to the IRS. It takes the IRS about 3-4 months to process an amended return
If you need to prepare a return for 2015, 2016, or 2017 you can purchase and download desktop software to do it, then print, sign, and mail the return(s)
https://turbotax.intuit.com/personal-taxes/past-years-products/