Also, I know I could just chuck the shirts and buy better quality ones, but I'd like to try to work with these.
Most Helpful Guy
I'm not sure other than replacing them. Have they faded with constant laundry loads or something?
Most Helpful Girl
The only thing I could think of is wearing something underneath them, but you said you didn't want to do that. I don't think there is anything with the shirts themselves that you can do...
You could try wearing a similar colored bra as well in hopes it doesn't show as much.
There are some tank tops that are kind of lighter, for lack of better words. Like look in the sleepwear section and look at night camis/tanks. For example I have a few Jockey ones that feel so light I don't notice them under shirts. They feel different to me than my actual tank tops lol, its hard to describe.