There's totally such a thing as a shitty sports bra, and a really damn good one. I hear it all the time, "I can't run because of my large breasts." As a woman who's pretty busty -- I am want to tell you that you can run, and you can find a sports bra that will help support those amazing jugs of yours.
Example Of A Shitty Sports Bra
If you're busty, please avoid this bra. No wonder you feel like you had to layer this sports bra up with other bras and fitted shirts. The problem with these kind of sports bras is that they do not offer any kind of support. And a lot of the time, they don't even provide coverage. The day I tried to jog in this sports bra, was the day I realized I was better off just holding on to my boobs.
Example Of A Really Good Sports Bra
You want to find a sports bra that has full coverage, underwiring, and wide supporting straps. Yes, these sports bras exist! They cost just a bit more than your standard sports bra, but it's worth it. The first time I slipped into my super supportive bra, it literally felt like my boobs were like feathers. Running was so much easier!