I'm still inclined to think undertired. I'd start with the first A time and add ~15 minutes on to it and see if he sleep longer than 45 minutes. If so, it was an easy tweak. However, if he suddenly starts taking 30 minute naps and wakes up very cranky, 15 minutes was probably too much and he was probably overtired. I'd then scale back to ~10 minutes more A time. So, you'll just have to keep an eye on it.
Then, once you've got the first nap figured out, follow the same pattern for the rest of his day.
Anytime LO takes a nap shorter than about 1.5h, the following A time is reduced to prevent OT at the next naptime. It means that the routine is a bit off for that day, but that's okay
It's normal. Also, a good nap is anywhere between 1.5-2h at this age. My DS never took a nap longer than 1.5h until he switched to one nap/day. If your little guy doesn't take 2h naps, that's perfectly fine. I know Tracey mentions that in her books, but it's more of a guideline than a set expectation, iykwim.
Here are some links that I think might help:
http://babywhispererforums.com/index.php?topic=64158.0http://babywhispererforums.com/index.php?topic=164029.0Give this a shot for a couple of days and let me know how you're doing