Exclusively Pumping: Milk Supply Constant

It is not recommended to reduce number of pumping sessions as it is signalling your body that you do not need to produce so much milk so frequently. My baby was about 5kg at 3 weeks too and drinking about 100-120ml per feed. I produced about the same amount as you during that time but my yield increased eventually. You can try replacing one of your pump sessions with a power pump session to try and increase your milk supply. Drinking lots of fluid helps to increase milk supply as well. Don't be too stressed about increasing supply as well. It is true that we should aim for 3 hourly pump sessions but I feel everyone is different. I couldnt wake up or keep to the 3 hourly pump sessions, hence my pump sessions can range from 3 to 6 hours interval which is not very healthy if I want to increase supply or maybe maintain but I just cannot keep up with pumping every 3 hours. It is true that if you drag longer hours in between pump sessions you may pump more during that session but overall milk supply does not really increase. So now I pump about 5-6 times a day, about 3-6 hours interval, each pump session getting about 120-200ml depending on how long the intervals between pump sessions are. I get about 800+ml a day, which is enough for my baby or rather slightly lower than what he takes as he can drink up to 1 litre a day but it's okay as I also supplement with formula sometimes and I am satisfied with just enough supply.