There is info in the following sticky which is located at the top of the L&LL page. Syringe & Insulin Info. Do your syringes have 1/2 unit markings? We all do our best to eye ball those in between doses. It would be good to get a +3 or +4 after the no shoots to see what Simba is doing.
Many cats drop lower at night. Mine often did. I suggest setting an alarm somewhere between +5-7 and test. You could vary the time and see what is happening. Since lantus is dosed based upon nadir it will help a lot with dosing.
Yes good idea wasn't thinking we had tested him before +4,+6 when he was on the higher carbs Iams food we will try to do that or at least do this weekend
Many people here use digital calipers to help keep doses consistent. You can purchase a 4" digital caliper from Harbor Freight. We have a post on how to use them.