Hi,
@EJMJones , the way you are analysing numbers as a newly dx'd T1 is pretty impressive, and will serve you well once you get levels down to the more usual 4 to 7 range.
But don't be in too much of a hurry to get there. Your nurses are correct: if your bg drops too low too quickly, that can be damaging. A deep sea diver gets brought up from depth in stages to avoid the 'bends'. So it is with T1 too: a slow, staged reduction over a month or so. You're in the T1 game for decades now. What happens in this first month or two will have no long term consequences.
I do a face palm every time I read T2s telling newly dx'd to immediately cut out all carbs. That's pretty much guaranteed to over-express vascular endothelial growth factor, vegf, which will damage eyes. Ignore anything a T2 tells you - it is an entirely different medical condition.
You're working the numbers well, but the reason they're not working out as well as you want is that your levels are high.
Injected insulin works in different ways depending on levels. The numbers you mention would probably have worked well if you were in a 4 to 7 level, but not so much in the teens. Be patient, you'll get down to 5 eventually and the calculations will become more predictable then.
Although, having said that, it's T1, so, sometimes, they just won't!