Whats wrong with me.

I feel like I am constantly being judged and picked apart. I feel like people think I have it easy being a stay at home mom of a one year old and 26 weeks pregnant. I have been sick for three weeks now. My one year wedding anniversary is right around the corner and I feel the lowest I have ever felt. My husband and I can't seem to have a conversation that doesn't end in fighting or yelling. Right now I just feel like the world's worst wife, worst mother and worst person ever. I just want to be happy but I don't know what's wrong with me and why I can't just be happy.