Subscribed to the second and link. I like to lurk/sort by subscribed and new and will try to comment when I have something to contribute. Niche communities are hard to form without a decent user base, but a general recommends community seems like a great idea.
This isn’t about imperial vs metric, it’s about measuring by mass vs volume. A good example here is flour. Weighing out 30 grams (or about 1 ounce) of flour will always result in the same amount. On the other hand, you can densely pack flour into a 1/4 cup measuring cup, you can gingerly spoon it in little by little, or you can scoop and level. When you do this you’ll get three different amounts of flour, even though they all fill that 1/4 cup. Good luck consistently measuring from scoop to scoop even if you use the same method for each scoop.
If M doesn’t want to wear a sports bra because that brings back traumatic memories don’t force it on her. The way your post reads, it sounds like it was your idea to try it again - not her’s. Your wording makes it sound lik she wasn’t interested in doing it, but you tried talking her into it anyway. It shouldn’t be surprising that it didn’t end well.
Is M seeing a therapist? That’s probably the best place to start if she’s not doing that already. Don’t suggest she go because dhe’s not wearing a sports bra anymore. Honestly, who cares about that. She needs to go to help work through her trauma. She might never dress provocativly again, but she should at least feel comfortable in her own head.