Your best bet would be to download a copy of your 2018 tax transcript from the IRS. A transcript is an abbreviated version of your return, and it contains your 2018 AGI. You can use the link below to get your transcript.
https://www.irs.gov/individuals/get-transcript
Other options are included in the TurboTax FAQ linked below.
https://ttlc.intuit.com/community/agi/help/how-do-i-find-last-year-s-agi/01/25947
*** I am NOT a tax expert. I am a seasoned TurboTax user, and volunteer to provide assistance to TT users. Nothing I post is to be considered TAX ADVICE; I bear no legal liability for responses.***
