Proud new momma with a few questions!

Buy a cheap postage scale from Wal-Mart. Typical rule is you want to se a slight bulg after she eats. So just slightly bigger than her thickest part of her body. It less stressful on the snake to feed in the same enclosure.

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I've actually seen instances where snakes fed in a separate enclosure will be more aggressive(or at least defensive) than those fed in the same enclosure they live in. So yeah, because of that and stress levels, I'd definitely also say feed her in her home.

You can get a digital kitchen scale (just make sure it displays in grams). Like someone else pointed out, you should see a slight bulge-so you'll want the prey to be slightly larger than the circumference. If you are feeding appropriately sized prey, you only need to give one item per feeding every 5-7 days.