S.A.
Our doctor said that at this age they don't need the night feeding and that by replacing the nursing with some water then they stop waking up out of habit because they aren't getting what they really want (to nurse). Either use a bottle or sippy cup of water that you can keep by your bedside.... your son should be sleeping 12 hours straight at this age.
Hope this helps - good luck.
blessings,
Stacy