Is a modern modest dress without an abaya, like a loose shirt and trousers, permissible for women?

So there are certain conditions that need to be met. Number one, the aura needs to be covered. Number two, it shouldn't be transparent. Number three, it shouldn't be figure-hugging. And number four, it shouldn't be anything that attracts undue attention. If those criteria are met, then the clothing that you wear will be fine, and whichever clothing that is that you're comfortable with, insha'Allah.