Jordan.
Voltage readings tell you nothing about the condition of the battery. To do that requires either a modern professional tester or the ability to test during a 200 ampere discharge, neither of which are available to most people. Nor does the fact that the battery cranks and starts the engine mean that is in good condition.
The electronics on the car require a stable power supply, not just any old voltage between 10 and 16 volts as was the case years ago. A failing battery can not supply that stability, leading to spurious electronic faults that come and go at random. Limp mode, loss of radio presets, loss of air con are some of the faults that can arise.
The age of your battery is not as important as its internal condition which can only be tested as mentioned earlier, though a life of five years seems to be all we can expect nowadays. I suggest you buy a new battery of decent quality, not one of the cheap unknown brands, and get it coded to the car to avoid spoiling it. Exide and Varta are two names that come to mind, though other folk in the forum can advise better than me.