Not sure if this has been mentioned in this chain (I skimmed for content) but a small anti-chafing stick can in handy, not only for intimate areas, but for feet/toes, around the neck, anywhere in fact that moisture and friction and fabric cause...
I recommend the Air Control sports bra by Anita. Great support without underwire.( I found my underwire bra hurt where it got overlapped by the pack straps, after wearing the pack all day). Plus you get good control without the cups being thick...
Although I must admit that I am recently quite amused by many of your questions and pre-worries I can relate to this question.
A very good brand is Anita.
https://www.anita.com/en/momentum-sports-bra-maximum-support.html
When I bought my new...
This site is run by Ivar at in Santiago de Compostela.
This site participates in the Amazon Affiliate program, designed to provide a means for Ivar to earn fees by linking to Amazon