There are a few extra steps that you will need to do after the original migration to move your PST files over. You can only move one PST file at a time, so if you have multiple PST files this process will need to be done for each folder.
If you have not already, you will need to install Google Apps Sync on your Windows side. For instructions on how to do that, Click Here.
Run the Migration and Syncing Tool
Select Google Apps Migration from the Start Menu
You will open this a second time after you have run the full migration of your Inbox, Contacts, and Calendar events.
Your PST Files will be listed with your other Folders
It will be the document with the Outlook symbol in the top left hand corner, and your name printed underneath it.
(You can only select one PST file at a time).
(This is the default location and name of PST files. If you have moved them elsewhere or renamed them then go ahead and select that location and file)
A status bar will open and show you the progress of your migration.
Select OK when the Migration has completed.