how much milk?

How much is normal amount to pump after feedings? I only have a crappy manual pump & only get about 1/2 an oz when I pump after my baby has ate. I never could pump w my other 2 kids, but seemed to have way more milk. Bc i leaked like crazy & when they were eating if they let go, it would squirt all over their face. My baby is only 8 days old & she won't suckle. Wonder if its Bc there's not enough.