I agree with Kris that 2u is likely too low, but I'm going to suggest an alternative way to approach the dosing. Since your kitty has been up at 4.5u, after this cycle you might try 4u and see if you're able to get two consistent cycles. If you're still having to stall, then try 3.75u, then 3.5u, etc. and work your way down instead of cutting the dose in half and working your way back up. My reasoning for that is that you're monitoring enough that you can keep your cat safe and it avoids leaving him/her high for too many cycles, especially given that he/she (I'm sorry, I don't see a name or gender for your cat) is already getting some pretty high numbers.