I'm at about 2 years on my original battery. It still is holding up, but cold starts aren't as crisp as they used to be. Takes a little longer to catch now than it used to. Probably time to replace soon.
Batteries typically last 3 or 5 years depending on the battery rating. If they fail sooner than their rating, they are typically replaced free of charge.
You don't have your location listed so I don't know your climate but a hot climate can cook a battery and shorten its life span. Here in Thailand batteries are only warranted for 1 year due to the excessive heat. What we do here is once we get home from a drive we raise the hood to dissipate the heat faster. Next time you need a battery get a gel battery as they are not effected by heat or cold.
It is very possibly due to being short tripped causing the battery to not get a full charge often. Short tripping and low mileage is bad on your car for several reasons, including it puts extra wear on the oil and electrical system. To help preserve your vehicle, maybe try taking it for a good 30 minute freeway drive once a week?
If you dont drive it often look into a battery maintenance charger. It will keep the battery happy. Many short trips are hard on a battery because it may not be getting charged back up. Example not real numbers. If it took 5% of battery capacity to start the car, and you drive it and charge it back up 2%, and keep doing this it can damage the battery once the voltage starts getting to low.