Sounds like you're doing fine.
I resumed cycling in August 2015, after a 30 year I-hate-us. I intended to ride the three miles home on the heavy but plush comfort hybrid I'd just purchased. I made it one mile and collapsed on the side of the road. Fortunately a city bus was only a few hundred yards away. The driver scooped me up, showed me how to put the bike on the front carrier, and dropped me off in front of my apartment even though the official stop was down the block.
Between asthma, Hashimoto's and a busted up back and neck I kept my goals reasonable. One was a 12-mile round trip to and from a favorite local outdoor theater. I made that by the sixth week, with rest stops along the way.
Hills were always my nemesis, even when I was younger and occasionally rode solo and group centuries (100 miles or more). So I'd tackle nearby hilly routes. Even if the total distance was only three miles I'd call it a win if I could ride the entire way without walking the bike.
No specific distance goals for the next several months. I'd set a goal for a place to ride to and take as long as I needed and as many rest stops as I needed to get there. Progress came very slowly.
For my one year anniversary of resuming cycling, in August 2016, I set a ride-my-age goal of 58 miles. I went a bit over, 63 miles, riding 20 miles in the morning, resting a bit, then riding to downtown to join some friends for a casual group ride, then rode home again. Since then I've ridden several 40-60 milers in a day.
After completing that I decided I was ready for a somewhat lighter bike and got a good used early '90s steel mountain bike. I added riser bars for comfort since I still have a lot of neck pain from a car wreck. The second bike was much lighter than the first and a better fit, so I rode farther.
My average per month has gone from 100 per month the first year, 200 the second, and 300-400 per month now. Mostly I ride 20-40 miles at a time, 3-4 times a week. With family stuff it's hard to find time to ride more often or longer on any given day.
Last week I bought my first drop bar road bike in more than 30 years, a good used '89 Centurion Ironman. Still not sure I'll be able to get along with the more aggressive riding position. Due to neck pain I'm limited to 10-30 miles per session, and I'm not really any faster despite the more aerodynamic position. It's much more uncomfortable, although the bike fits me properly. But I'm working on neck strength and flexibility, and may swap the skinny 700x23 tires for something a bit wider that can safely be ridden at lower pressure -- our rural chip seal roads are atrociously uncomfortable.
But any ride is a good ride. Some days I'll just ride around the block for a few minutes to get the blood circulating. Helps.