I have the Manuel pump "made for me".

My right breast gets it to suction so well that sometimes it's stuck on too well when removing. You can feel it pumping but it never hurts.

My left breast just doesn't want to suction. It is still pumping but not attached like the other side. You can't feel it pumping but can see the nipple moving as you pump. Doesn't hurt but the slightest movement and the whole breast just falls out of the cup.

Is this normal? Is it meant to be loose or tight?