Still confused

I understand that the fasting number is taken when u get up in the morning.
But you are supposed to test before any injecting insulin too.
And my kind of insulin is adjusted on that fasting number and has to be injected 30 minutes before eating.
But I get up 3 hours before injecting so that measurement isn't going to be a fasting number. Because I have a suger free coffee with some cream and sweetener (which does increase my numbers).
This all has to be this way because for approximately 30 years I haven't been able to eat before noon.
So I've been mostly having just a drink or some candy after the 1st injection. (It's 2x a day insulin).
How do I get around this or is there even a way? (NOT with switching insulins. That's not an option.)

Which measurement would I use for adjustments? The first one when I get up or the one 3 hours later just before injecting?
3 hours can make a big difference in numbers.