Hi Lynners, sorry you had a rough day
I've gotta say, my LO didn't really grow out of 40 min naps until after 6 months. At the 5 month point, I was trying a set routine from a different book that either (a) just didn't suit my bub or (b) my bub was still developmentally in the catnap stage, as it was never consistent whether we would get 40 min naps or 2hr naps. I'm sorry, that's probably not what you want to hear! I'm pretty sure it was around the 6-7 month mark that things really settled down. My LO has almost always been a good night sleeper (much better than day sleep for many months) and she doesn't seem to really be affected overnight by OT.
I have learnt by trial and error that if my LO only short naps the morning nap, I put her down 30 min early for her afternoon nap; and if we have a really rotten day (2 short naps, or only one nap) I put her to bed 30 mins early, and she seems to catch up overnight.
I guess you are in the position where you don't have to do the school run for a few weeks(?) so can try a few different things if you want and see what works best. I'm sorry, I can't tell you exactly what you should do, can only give you my own experiences.