I go by Peter at present-- I had been using Michael for maybe a couple of weeks beforehand but Mom texted me to suggest something different, and Peter came up. I thought it was a serious suggestion and adopted Peter because I thought it was a decent fit and I could be accommodating toward Mom, who was having trouble adjusting to my transition, but it turned out she was being facetious and doesn't care for the name. To rectify that, I let her choose my middle name, and she opted for Knox, which I like quite a bit. However, I've recently come across the name Cannan, which I think suits me better than Peter, but I'm not sure if it's worth having people re-adjust at this point (I've been Peter for close to eight months now).
D.K., have you considered James as a second middle name? I think it sounds great with Noah, for some reason.