How do i get my 7 month old to sleep better?

My son is 7 months old and from day 1he has been a horrible sleeper..i am exhausted. ive tried everything, making sure he is feed enough, rocking him,singing lullabies, making sure he is comfortable and the temp in the room is right, etc.. i dont know what else to do. he gets up every hour and a half to 2 hrs, crying, either to be rocked or for a bottle. He is teething(he just got his second one in so maybe that could be it, but he is cranky all day from lack of sleep...HELP!!!