Milk talks on Instagram: "How to know if it’s a pump issue or a supply issue One simple way to check is this: ➡️ Hand-express right after your pump session. • If you can collect more than 20–30 ml by hand, even after pumping, it usually means the pump isn’t emptying you well — check flange fit, valves, suction, or motor issues. • If your pump output matches your baby’s needs and your hand-expression after pumping yields less than 20–30 ml, then your pump is working well and your supply is establ