This doesn't change anything. It retrieves the same year and day, but instead of the month it retrieves the day of the week in the month (Calendar.MONTH = 2, Calendar.DAY_OF_WEEK_IN_MONTH = 8 so 6 more than Calendar.MONTH).
What you want to do is modify the calendar to add (hint, hint) 6 months, then retrieve the 3 values again.
Oh, and the months are 0-based; Calendar.JANUARY is 0. To make the months 1-based use the following:
This will always work, even if Calendar.JANUARY would ever change to 1 (which it won't).