R.M.
Hello A.,
When a child I'm working with changes their behavior, becomes more clingy, angry, throws more tantrums, I first look to see if they need something I'm not providing. Children cannot say, "you know Mom, I'm feeling lonely right not and I'd love a heart to heart." They just don't have the words.
While in no way am I saying you're doing something wrong, I KNOW no matter how much attention you provide kids, sometimes it's just not enough for them. I do suggest you set aside time each day for you & your son time. This is time you two can talk, play or just be. It's not dinner or TV time, just you time.
When your son gets clingy, look at the clock, tell him what time it's 'you' time, you could also write the time down and let him be in charge of watching the clock. Also, when he starts getting clingy, ask him what he wants to do during 'you' time. Remind him you need to get your work done or you can't have you time.
This will take time, and you will need to be consistent about your approach, but I think it will help.
I which you the best of luck. You have a lot on your plate.
R. Magby