Question about checking an undertone at home

I have narrowed my notes to Deep Summer and Soft Winter for now. Swatches on a screen feel less useful once daylight changes. I started by taking photos beside a north-facing window at the same hour. To reduce distractions, I compared the shades without makeup or statement accessories. Deep shades gave contrast, although a few made my under-eye shadows more noticeable. Muted cool shades appeared balanced, but I want more than a personal hunch. I tried to describe observable effects instead of deciding from a favourite colour. A neutral color analysis might help me sort the notes without forcing an immediate seasonal conclusion. I see online tools as prompts for observation, not as final proof. Which repeatable signs helped you tell deeper cool colours from softer cool colours? I am looking for steps that remain useful when the weather is grey. I would prefer a reliable routine over a confident but rushed conclusion. I hope that a slower record will make my final comparison less influenced by mood. Thank you for any practical perspectives you can offer.