1) yes, you are fine. while the rule is "6 months before going on Medicare", that doesn't carry back to the months before you turn 65.
2) your calculation is also correct
When you file for 2022 tax return, there is a series of checkmarks on form 8889. For the calculations to work correctly, you want to be sure that months Jan-Oct are marked as "self only" and the last two months of the year are marked as "Medicare or None" .
TT will ask whether you had Medicare at any time during 2022. You should answer "yes", then you will see the 12 months and the checkboxes.
