Is Something Tougher than Positive Discipline Needed?

Question:

I am the mother of a 3-year-old boy (his birthday is actually tomorrow) and he is also a student in my Montessori school. Over the year he has been at school we have had many challenges with me being “around” a lot and never really having that separation from me that other kids get. (I don’t teach anymore but still sub sometimes in his class.) He recently turned a corner, seems to be doing well and is settling down. He is also very bright. He has a fantastic vocabulary and wonderful memory retention. He is independent and capable.

My question really is about Positive Discipline. We have practiced Positive Discipline since he was born and have adjusted as needed based on his development. My problem is that sometimes I feel like he needs something tougher than Positive Discipline, but then I know that the traditional ways don’t work. He is just so wild sometimes I get really frustrated. 

He usually does “annoying” things when he is very happy or likes someone a lot. We will be cuddling and suddenly he will head-butt me or he will be with a friend and out of the blue he will grab their work and make them cry. He seems like he is constantly seeking attention from everyone but he gets so much attention to start with!

I can’t ignore him sometimes because I have to help solve the conflict with the other child. He has now taken to saying “sorrrrry” if he does something to me and I ignore the behaviour. Interestingly I always said to him, “Ask your friend how you can make him feel better” instead of insisting he apologize. He would reply “I don’t want to; I just want to say sorry” As you can tell I am conflicted and frustrated! Please advise.