Big hugs. I found naps and routines very unpredictable for both of mine for the first year. It's not anything you're doing or missing, it's just the way little babies are, constantly changing and developing so nap times and routines keep changing too. The short naps might just be a blip due to a developmental leap, or teeth or some other baby reason. Those A times sound about right for his age. I'd hang on in there, and keep the times you had. I think the better naps will return when whatever has thrown him off right now has passed.