Michelle,
thanks for the tip. I was not really sure.
What a weekend!
I was so determined to get rid of NW and most of all of OT, but everything and everybody were against my plan!!!!
First of all, he's teething again, canine teeth are coming in, very aching.
Then our weekend schedule was so full...too busy...and so hot......

On friday afternoon we had a party at DC. Was really nice ad DS had a lot of fun, but he was really tired and what with one thing and another he went to bed at 9 pm!! Woke up several times due to teething and OT and was up at 5.45. Napped 9.30-11 and then napped again 4.30-5.30. At night we had dinner with some friends and he refused to sleep until 11 pm!!!
Then woke up twice and was up at 6.30. But, as we realized everybody in the house was exhausted (dog and cat included) we took him to bed with us and slept til 8.00 (kind of miracle for us).
Sunday was calm and relaxing and he was asleep by 7.30 pm, woke up just twice and slept till 7 am!!!!

Anna and Michelle, now I am sure: you both were right.
OT IS THE KEY HERE! (but these days teething is to be taken into consideration too). Yesterday he had an 11,5 hours day instead of the usual 13-15 hours, A time never exceeded 5 hours and things really improved.
I know maybe I went wrong taking him to bed with us sunday morning, but we all needed some rest and, considering how the day went on, I think we did the right thing at that moment.
Hope last night was not an isolated episode.....
I'll wait comments...

TIA