I've had my '11 since new have have 63k+ and run the AC every single day without issue....
Yes, that is exactly what happened, at the end only the passenger side had cool air, then no cool air at all while idling at lights, traffic, etc.I had mine recharged about a year plus ago, no issues since but was doing the same as you mention of slowly just not getting/staying cool.
Ac is blowin strong in my Dec build date 2012 EX. :hope: