I know this is easier said than done, but try not to worry too much. Your LO is still soooo young, and getting through those sleep cycle transitions is a skills he's working hard to learn! It's absolutely common and expected for very young ones to need some help to get past 45 mins.
As PP said, don't be afraid to resort to accidental parenting to get him caught up on sleep towards the end of the day - all the practise you've put in wont be put to waste. I think a great thing to do is to head out with him in the pram, nicely swaddled, and go for a good long walk. It will do you both good to get some fresh air, it will clear your head, and lots of babies nap miraculously well when on the move in the pram.
Try sneaking in to him at 35 mins and laying a hand on his back and seeing if you can ease him through that 45 mins transition. If you can't, and shh-pat isn't settling him back to sleep, don't worry about it. Get him up, enjoy some quiet, low-key A time, and get him down for his next nap early - don't leave it until the next 'scheduled' nap time or you will definitely end up with an OT baby boy. It's totally fine to have lots of short naps if you can't manage fewer long ones.
(((hugs))) enjoy each other. These precious days when he is so tiny pass so quickly.
anna
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