Everything is based on the UY of the travel, and not on the calendar year.
So, as mentioned, your Feb 2012 trip can only use borrowed 2012 points since it takes place in the 2011 UY.
The easiest way to figure it all out is to first figure out the UY you are traveling and then go from there. You can always use points that are banked from the UY prior to travel, the UY of travel, and borrow points from the UY after travel.