4 year old acting out closer to my due date

So I’m the lucky parent that always talks about how perfect my child is. She’s 4 and she is always nice, polite, and just an all around good kid that never needs correction…

But she is like a child I don’t even know sometimes lately. I’m 34 weeks pregnant and a stay at home mom so we are together 24/7. She has been so mean to ME and only me. She doesn’t listen, and she does things she knows she shouldn’t do. She still acts the same for everyone else. I feel like she’s resenting me for having another baby, and I’m scared for how she will react when her little sister gets here the end of November…

Has anyone else dealt with this? I try to be patient, and redirect her, and reassure her that she’s still my baby. But I’m tired..and hormonal and just really don’t know how to fix this. I don’t want our relationship to be ruined because we’ve been butting heads so much lately…