Amy, you sound so much like me that it's uncanny. Your use of both AT2 and human meter reminds me so much of myself. Believe me when I say, mixing meters takes a lot of self discipline not to panic over readings on either meter. It tends to confuse the situation when you are so early in this journey. I however was dual testing on the same drop of blood each time I tested so I had comparisons for EVERY test. I admit I like and trust my pet meter the most despite my use of a human meter BUT I also came to the conclusion that unless my girl was in very low numbers on the human meter, the difference didn't matter. I know my human meter (not the one you are using) reads low in low ranges so when I got a low human meter reading, I double checked it against the AT2 to decide what the best course of action was. You have not encountered any readings low enough to be affected by this difference yet.
When I first mentioned a human meter to my vet she looked at me like I had horns growing out of my head. Fast forward and my vet emailed me wanting to know what normal readings were on a human meter because she had a client who insisted on using a human meter. A human mete is just as good as the AT2 but the numbers will read lower.
You are so early in this dance and getting most kitties regulated is a marathon NOT a sprint. You are going to have to be patient and let the numbers from ONE meter guide you as to how to proceed. Your vet is not going to be available to guide you 24/7 so you need to gain some confidence in your ability to interpret and deal with what Salem throws at you. I understand your desire to keep your vet involved but to be honest, most of here deal with dosing ourselves because we are the ones holding the needle and on duty 24/7.