I’ve done the same testing you have, Katie, and gotten similar results. I’ve tested myself for the diet root beer I prefer (A&W), packets of Equal, Orbit sugarfree gum and every sweetener I know I’ll come across. No reactions. I don’t give a second thought to any of them.
I understand people’s reactions about avoiding the sweet taste for fear of triggering cravings, and that sweet tastes might trigger insulin. I’m lucky to not particularly get cravings. My approach is to usually have sweeteners as part of a meal. My reason is that a meal is going to affect insulin and blood sugar anyway, so any effect of the sweetener is diluted (or swamped out) by the meal’s response. In general, I have one diet soda per day with dinner. Yes, there are days when I have two, but there are also days when I don’t have one at all. Like you, I use the erythritol in my coffee, and tea (if I’m having any). That means most days I have one packet of Equal (aspartame) and three teaspoons of erythritol. I’m not sure what’s in a 12 oz can of diet A&W, but I have that one can, too.