I need help finding my 2018 Form 5329 to determine what my (accidental) HSA excess contribution was.

[LinaJ2020]

If you filed with TurboTax, you can access your 2018 tax file by clicking here:  2018 access

Or

if you did not file with TurboTax, you may order a transcript from the IRS.  Click here Get  Transcript and select  "Get Transcript Online "  

For more information, see IRS copies

[santillanes-alma]

I did access my 2018 return through Turbo Tax, but I did not see the form on the 104 page document

[LinaJ2020]

So, did you even file a Form 5329?  can you check if there is an amount on line 6 of Schedule 2 and line 11 of Form 1040?  That will give us a hint.