Emily, unless you are having trouble shifting to your granny gear, then what is your reason for not using it? Is it because of that out of date mind set mumbo jumbo about it being for grannies? When I teach a basic bike class, the first thing I ask is what is your most important gear? And the answer is your lowest one! Seriously, use the gears you have. This does not in any way rule out switching out your cassette. My bike that I changed from a 25 to 28 was a triple and I used the granny gear a lot on bigger climbs. I had some smaller hills where I stayed in the middle ring, but basically it hurt my knees and slowed my speed to do so on anything over a 3-5% grade. This is especially important as we age. The goal is to keep riding.
I changed my cassette from a 25 to a 27, then to a 28 on my triple. I sold this bike to a woman who is a much stronger rider than me and she has no trouble using the granny on climbs. I would have bought a triple again when I bought my Silque, but they don't make them anymore.