In any relationship when the other party are being hostile they are usually feeling isolated, scared, unheard, unloved etc.

It hard because you need extra nurturing yourself while pregnant, but I would focus on eliminating negative talk between you and try and increase cuddles, smiles and understanding. When she backchats try and reframe it for her 'you really don't want to tidy your room right now, I hear that, perhaps you could suggest a time when you could do it'. Of course you need the patience of a saint to do this, so get DH involved as much as possible so you can take a breather if you're not able to keep calm.

When my kids challenge me I always lower my expectations and hold them closer. IMO you want to preserve your relationship with her above everything else. Negotiating situations with considerate language and respectful boundaries is a process kids learn very, very slowly and it's always three steps forward two back.