Hi Jenn, good job checking +2, I think you can call it a night for testing. For many kitties on Lantus, we find that the +2 is a good indicator of where the cycle will go. Yours is higher than preshot, so likely not much action tonight.
On a side note, I know sometimes it can be overwhelming, and when the kitties get grumpy, it makes it harder. Try to find times outside of the diabetes routine where you just give him a little extra attention. We can get so wrapped up we forget to just enjoy. If the growling continues, it may not be what you think, I'd watch for other signs of him feeling unwell.