hi there and welcome to BW
If your Lo ends up taking a short nap, it's important to shorten his next A time in order to prevent him from getting overtired as the day goes on. A 45 min nap just isn't long enough for him to be awake for his normal A time. So for example, if he wakes at 9:45 and you PU/PD for 45 more min to no avail, I would try keeping him up, feeding him at 11:00, doing a low-key remainder of the A time (something not too stimulating), then try for another nap say around 11:30-45. What is his current A time?
Often when this happens your routine looks more like EASASE. But shortening the following A time may get you a decent nap, then you can squeeze in a catnap and shoot for an early bedtime - make sense?