I started cycling a little less than 2.5 years ago, was exactly where you are now. It took me 5 months to build up to a 60 mile/2500 ft ride.

Now I'm one of those people who considers a 25 mile ride to be "short". Cycling builds upon itself and you can start to accomplish more and more once you've built a solid foundation.

I rode around 2000 miles before I even really started climbing. Someone told me that's what I needed for a base and that I needed a base before I could do much else, so that's what I did.

Within a year, I had ridden my first century, 100 miles/3500 ft. In the 12 months after that, I rode maybe 8 centuries, including two 10000 ft climbing centuries, three double metrics and one double century.

Since then, I've done climbing endurance races and have started time trialing. I have two road bikes, a TT bike, three power meters, a coach, and a zillion cycling friends. It really does all build upon itself and your progress will pick up.

One thing that works for me is to always have a clear goal, something I'm preparing for. Keeps things moving along nicely on the bike. Sometimes I think people have these vague goals, like "to get better". You really need something like "I'm going to ride a metric century on Sept 15". This is where event-type rides and races start to become useful. You figure out what you want to do and then how to get the goal accomplished.