'Routine' is one of the worst things that was ever invented for mothers. The number one Western mark of a 'good mother' is that she 'got her baby into a routine from early on'. No, the fuck, no, NO. I subscribed to this for DS1 and spent my time self-flagellating when I wasn't thinking about his sleep. I realised this was a total myth with DS2 and had a much, much happier mat leave. Sleep deprived for me, yes, but DS2 was much better slept than DS1 and I have no regrets about time wasted on trying to impose things on him that were a waste of time.
Most babies will not follow the same pattern every day (as you are seeing today, it would seem). Some babies will and, just to fuck with you, society or the parents themselves will put that down to marvellous parenting. No, they got lucky with a baby who likes to follow a socially acceptable schedule.
Some days will be easier than others, some will be harder. This has nothing to do with you. A baby who wants to nap and sleep on the breast is a normal baby as sucking plus a gutful of sleep-inducing tryphtans in BM make staying awake impossible. They're bloody hard work, and frustrating, when you've been reliably told from the start of time that babies sleep in cots and go four hours between feeds, but that there is the only conflict - expectation versus the reality.
On days when I had a nap dodger, I might abandon first nap attempt, then attempt again 15-20mins later, pulling out big guns - boob plus bed plus dark room plus white noise. At eight months old, I was confident enough to have him under the duvet with me (unless you're at risk of falling asleep like this, obvs) to make him extra cosy. That would then be Netflix on an iPad with headphones job for me so as not to disturb him to keep him asleep. Then I'd sniff his head for an hour or so while eating chocolate