My baby STILL won't sleep thru the night!?

There are children who don't sleep thru the night in a long time. My son is one of those kids. He is 29 months old, he still wake up around 3:00 am. He sometime sleep the entire nigth then he start doing the same routine night after night. At this point, he's sleeping in a nice & cozy full size bed with rails, but he still wake up. I turn the night light off & close his room door, but he still wake up, get out his bed, & walk from his room to my room thru the dark. He just want to be hug while he's sleeping. So, when he cries on the middle of the nigth, I just get into his bed to sleep with him until 6:30 am. His Dr. laugths a lot about this situacion. She has told me he'll eventually sleep thru the nigth, but he isn't ready. I have a friend who did the same until her son turned 4 & told her he was a big boy & would sleep alone from now on. My friend cried since her son wasn't needed her anymore. His Dr told me my son has taken me as his security blanket, so I have to wait until he grow up this issue. The only idea I can give you is to try to find what make your kid to sleep thru the night. Probably a blanket, stuff animal, a pillow, etc.