Why does my baby want to stay latched on constantly?

i have a six week old who is probably going thru a growth spurt but he will nurse for 30 min on one side then 30 on the other. Then,after a full hour, when I take him off,uming hes done, he will scream and cry and keeps making sucking gestures with his mouth. so, iI put him back on because i dont want to leave him hungry. He will keep doing this constantly. He drains both but wont be content unless he is latched on. One day I nursed him for over two hours and when I set him down he screamed and sucked his tounge, my husband looked at me and said "he's hungry""I've tried pacifiers he spits them out after a few min. Is there anything I can do? He has done this since birth and I know he is getting enough b/c he constantly has w/d diapers.