Re: 9/22 Pepper AMPS 109, +3 166, +5.5 55 - Dose ?
FWIW, I've never reduced the dose when starting a new pen.
Also, unless you have reason to believe your insulin has become "toasty" for some reason, you do not have to discard it after more than 28 days. The manufacturer makes this recommendation but we've found that as long as you are gentle with the bottle/pen, it can last a lot longer. I'm currently on day 51 with my pen.
I'd stick with the 15.5u. Those blues look good.