Congratulations Bill! Practice is often one of those things that is overlooked all too often. If you play every day, even if it is only for a few minutes; you can't help but be better. It's completely guaranteed that you will progress. You are truly seeing the results of that and I and the rest of the Guitar Tricks team extend their congratulations.

As far as calluses, remember that playing the guitar is a physical feat; much like being an athlete. You are utilizing your hands and arms unlike any other motion you normally do. It boils down to muscle memory and no age, size of hands, or mental capacity has much to do with it. The key is to fall in love with the process and it sounds like you are doing so. Enjoy the journey and keep us updated on your progress.

Good luck!