You and Hubby... need to take TURNS.... being with him.
He is also 4 years old, and can understand how to 'help' Mommy... AND I would get him involved in doing "chores" and helping things in the house....
he is at an age to be able to do simple 'chores' too, and realize the importance of "helping" the family, being a part of it.
And just explain to him, that there is a evening 'routine'...and Mommy has to do things... you of course have to cook dinner/clean up etc. That cannot be ignored. It is for the family.....
You and Hubby, need to take turns, being with him at this time period.
Don't feel guilty. It is home life.
And you do seem to spend time with him... and aware of his needs.
But... regular household things... cannot always wait or not be done.
So incorporate him INTO these things, have a daily 'routine' for him... and structure....
You work full time, come home and need to on a fly get dinner done, clean, bathe him, do things. You are not a bad Mom for having to do all this. BUT... you AND your Husband.... your HUSBAND... ALSO has to be pitching in.... with household chores and being with your son... too.
Not only you...
all the best,
Susan