Night time weaning

My lo is nearly 8 months old and since birth has been a milk monster! He was born at 6lb10 and has been steadily putting on 2-4lbs each month.

I have just got back from having him weighed and he has jumped up another centile. I really thought that by the time I start weaning him at 6 months his weight gain would stabilise but at 33 weeks he weighs 22lbs. After going through how many bottles he has and what he eats, the HV said the 'problem' of his rapid weight gain is that I still give him a bottle at night and need to wean him off.

Anyone have any babies of similar weight and age and what are your thoughts? Also any tips to wean him at night? I tried previously for 5 nights straight and he just screamed and screamed until I gave him milk. I probably shouldn't have given in but its hard when he nust need/want the milk? Or is it really habit? I'm feeling a bit down about it all and worrying that I've caused bad habits.