I feel like I’m going to break!

I’ve got two girls 2.5yo and 15month old. They both don’t listen to a thing I say anymore. I ask nicely, I ask again and then it turns into me having to scream and shout. And apparently to them I’m just a clown. I literally get laughed at. They both constantly moan and cry and I’m just so done with it. I feel so depressed and my days are just the same over and over. No matter how much effort I make to try and have a good day. It’s exhausting. I am constantly keeping them busy doing things with them and it just doesn’t seem good enough. I’m tired and also 12 weeks pregnant. Super stressed out and all I want to do it cry. I’m so over this now.