Babies go through a growth spurt round about 3 weeks, done it six times! I know it seems like you are permanently attached to each other, but it will settle. If possible I would try to avoid the top up with formula, as your body will make enough milk to feed him, honest, and the fact that he is gaining good weight means that he is getting enough. Not sure why HV is telling you to top up with formula and then breastfeed more at night, by giving the formula you are not increasing the milk supply. Good Luck xxx