To get USB 3 speed you need to have a USB3 device and a USB3 cable. I have the same model MBP with a USB3 external and it shows the proper speed in System Information. This is its System Information report.
I also have a new IMac with USB 3 and moved an USB3 external drive to it, but could not find a USB3 cable. System Information showed it as "up to 480Mb/sec" until I found the USB3 cable. Now it reports 5Gb/sec.
USB3 cables have blue plastic fittings inside the connectors; USB2 cables have white plastic:
I'm 100 percent with with my esteemed colleague Leroy on the "workhorse" comment. I will hate to see the day my 13-inch 2012 non-Retina is beyond use. The only thing that slows them is the factory 3GBps, 5400-rpm hard drive and that is easily corrected even by a novice user.
About a year ago I upgraded mine to a fast solid state drive and it feels as fast as new Macs. It was probably among the most successful Mac sub-models ever. There were in continuous production for over four years without any changes and are, based on reports here, the most trouble-free. I am completely committed to spending money to keep mine relevant as long as possible. I do not like the direction Apple has taken with their notebook line in recent years and unfortunately feel I need to avoid them.