I answered your original question too, and said my son gets 12-13 hours of sleep I believe. Afterwards I was thinking maybe I should go back and add that he does still wake up in the night, probably half the time. Mine is in a regular bed, so he is able to come in my room.
My opinion is that this is normal. Not ideal, but there is nothing "wrong" with your son. He hasn't learned to put himself back to sleep yet. We are working on that with mine, but because my husband travels a lot, I am skeptical that it will happen easily for us. I also do not think your son actually "needs" anything either. He just can't go back to sleep and needs your help to do so. What you need to work on with him to teaching him to self soothe. Do you have to rock him or pat him to sleep? Getting him to fall asleep on his own is crucial to getting them to sleep through the night. My son used to go to sleep on his own and stay asleep, but when my husband started going out of town, it all went out the window. I have finally gotten him to put himself to sleep again, but the staying asleep didn't come with it like last time. I think the big boy bed contributes to that, because he can just get up.
Try getting the book No Cry Sleep Solution for Toddlers and Preschoolers by Elizabeth Pantley. That is going to be my next step personally. I have had it recommended by several people. I am guessing since you do get up with him that cry it out isn't something you are comfortable with. Her methods do not require you to let them cry. I used her book for infants and babies to get my son to sleep through the night the first time around, so that is why it is my first choice this time too. Hope that helps.