Turbotax by design saves in a default format of .tax20nn where "NN" is the last two digits of the year. That is the file you "MUST" import from. If you import from the PDF file, you will "NOT" get everything. Doesn't matter if you used the online version of desktop version for your 2018 taxes. The default file format saves with a filename extension of .tax2018.
If you used the CD version to file your 2018 taxes, then the .tax2018 file is in the documents/turbotax directory by default, unless you took physical action to change it to some other directory. With the CD version, the .tax2018 file will only exist on the computer you used to prepare and file your 2018 tax return with, last year.
