M....My only advice is don't worry it will happen.
I am the mother of 4 ..3 sons ages 25,20 and 18...all 3 were trained within 2 weeks of their 2nd. birthdays. they were easy,absolutely no thought at all had to go into to their training. Then 3 years ago our daughter was born,and again at the age of 2 I thought I would began training her,well...she has a mind of her own. She turned 3 last May,just 3 weeks ago she began tt-ing the potty,out of the blue my hubby ask her if she wanted to go on her potty and what do ya know she went ,she got a princess snack as a reward. Well she went 3 times in 15 minutes just to get her reward. I was tickled. then I started trying to get her to do the poopy thing in her potty. I begged her,sat for what seemed like eons coaxing her to do it..to no avail,then yesterday she runs into bathroom to potty and came out and said "I did it,I went poopy" sure enough she had...now the trick will be ,will she hang with it.
My point is,all children are different,some like my daughter are extrememly headstrong,no amount of pushing her was gonna work. It was gonna be on her terms.
Don't let others shame you about your sons training. I personally found this part the most stressful part of the whole training experience. Everyone (expecially grandparents) have their ideas about when you should start training. My mother and in laws believe you should start at 6months....I personally think that 6 months sounds absurd. You will know when your son is ready,and actually until he is their is very little anyone can do to change his mind.
So just try to take it one day at a time and not let it bother you,they grow up way to fast.