Also, might be a good idea to invest a few dollars in a scale. I picked one up on eBay for around $12, but you can find them at Wal-Mart pretty cheap.

As far as eating, I've had a couple of mine that have had the same response. I went up to rat pups, and they seemed to be a little more full afterwards. Might be a good idea to up the size of the prey or double up on them.