You are lucky... that he has not gotten Constipated.
Because, constipation can take MONTHS to normalize.
Constipation, in potty training Toddlers, are common.
It occurs because:
They are not ready to poop in a toilet, but are not allowed to poop in a diaper. THUS the child, then purposely "withholds" their poop. Thus, they don't poop at all. Thus, they get internal pain & medical problems. Thus, they get emotion based problems because of the pain and anxiety. Thus, they get afraid to poop. Because, it is PAINFUL to hold poop in and the poop gets HARDENED internally, and then cannot come out or causes great pain, when it does come out.
Constipation, can also cause medical problems such as:
Encopresis
Blocked bowels
Bulging bowels
etc.
Now, I know this because, my daughter had stress and anxiety about pooping, when that age. We did NOT force her or anything about it. But it was her emotions not ready for this yet. THUS, she withheld her poop. Got constipated. Then we had to take her to a Pediatric Gastroenterologist. He said, that EVERYDAY he sees Toddlers like this... because, they are NOT ready to poop... for that stage of pottying, yet. HE said, to LET AND ALLOW the child to just poop.... even if that is in a diaper. The world will not end. The child will then be without medical problems and constipation.
WHEN ready, the child will learn to poop and be emotionally ready, for it being in a toilet.
It can take MONTHS for the Constipation... to normalize...and via using prescriptions and other things, to soften the poop. AND for the child, to emotionally.... feel better.
So, this Specialist said: Poop 'training' is 2 fold:
Emotion based and,
Biological based.
Now, again, let your son be.
You do not want him to get Constipated and withhold his poop. This is unhealthy. To say the least.
Your boy is young.
There is no rush.
Pooping in a toilet, is OFTEN that last stage and phase... of potty 'training.'
THIS is very very very, common.
In both genders.
Both my kids, have NEVER EVER went backwards with potty training, just because they had a diaper on for pooping and for sleep.
For naps/bedtime... remember that night time dryness, does not occur until even 7 years old, and this is NORMAL.
Sleep time dryness, is a SEPARATE process, than daytime pottying.
It is about the physiological development, of the body.
For naps/bedtime, my son who is 4 almost 5, still wears a sleep diaper. He does NOT get confused.
My daughter, still wore a sleep diaper even when 5 years old. Normal.
She was still wet during sleep.
At 7 years old, my daughter still had, sleep time pee accidents too.
That is why, you should buy a Waterproof bed pad, to put under the child, to make clean up easier. My kids' sheets do not get wet/soiled when they leak or have accidents, because, I have a waterproof bed pad, directly under them.
All gotten from Amazon. I have 4 of them that I rotate out as needed.
No biggie.