30 gallon is large for a 2 ft snake. I personally wouldn't move beyond a 20 until the snake is pushing 4 ft. A 20 gallon is 30" long so even at 4 ft they can strech more than 60% of their body out. Also, you say that she has only bitten you after she has eaten but that you wash your hands and pick her up gently. This sounds like you are feeding her in a seperate tub/tank. If so, it is unnecessary and you could avoid being bitten by just feeding in her everyday tank.