Congrats on the improvement! This time last year may longest ride was around the same distance as yours when you started, 6 miles or so into town and then I would ride back home later in the day. Fast forward to now, my longest ride is about 125 miles, I've podiumed a few races, and I no longer feel like I have to plan my rides so I don't over do it. Keep on going! The better your endurance on the bike gets the more fun exploring on your bike will be!