hugs.
so you had 45 to 50 min naps at the beginning of the day and then 30 min naps by the end of the day. i think he was UT first thing leading to a short nap, but after that he got progressively OT as the day went on giving you even shorter and shorter naps.
so tomorrow why don't you try 1 hour 20 min A time when he wakes up tomorrow. if the first one is a long nap try 1 hour 20 min A time again, but if it's only 45 to 50 min nap try 1 hour A time and if it's only 30 min nap try 45 min A time and see what happens.
after a short nap the A time is going to be much shorter. i think he was really OT especially by the end of the day which gave you trouble at bedtime.
if he is OT and having trouble settling to sleep (taking 45 min and putting going to sleep off even longer when you already know he's OT) it may be a good idea to do some AP on purpose to get him to sleep and catch up on some sleep so you can then go back to getting on a routine. so i mean letting him sleep in the car, stroller, slong, wherever he usually has a good long sleep to catch up.
what do you think?