Same here, I tried different brands. Doing the same as you.
Experiencing the same thing. I will just measure with 🍼 first before putting into storage bag.
The only way the measurements work is if the bag is fully expanded and standing up, but it’s not much help if you only want to put a bit in
You could weigh them and convert. Or go the extra step with measuring in a cup/bottle. Or like mentioned above, bag open and standing. Keep it consistent so there isn't much discrepancy.
I have the same issue. I have taken to pumping and measuring in the bottle then putting into storage bags so I know how much there is as well.