iirc, when dear son just turned 1yo, his nap time was: 11.30 to 12.30 and 3pm-4pm. total 2 hours nap a day. but at 15mth old, i change his nap time to 12.30- 2pm (sometimes 2.30pm). i sut down his nap time cos he cant sleep well at night, always wake up in the middle of the night dont wanna sleep.
if your son only wants to take 1 nap, maybe you can switch his nap time later? nap from 12-1pm onwards??
i think his fussiness at night could be due to over-tiredness. my son behaves this way when he is over tired.