Wear a gents banian or half slip with broad straps between bra and shirt. This is normal method of minimising the bra show thoruh shirt/tops etc. What is the bigh issue? If u want to demonstrate your bra and earn high profile then matter is different. If you wear a bra, any way people are going to notice.

Buy a white bandeau

Try a braulette or a bandeau

A bandeau would be fine to wear underneath it, you can get them in plain white to match the shirt, or in other colours if you wanted to add more to the look :)

A bralette is like a bandue but a little longer u can get them from most teenage clothing shops