Short temper/low patience

I currently have a 16 month old son who is my entire world. I’m 6 weeks pregnant and, where as I typically have amazing patience, I have ZERO now. I’m getting very irritated with the temper tantrums and have to just take a small break so I don’t yell from frustration. I understand that he’s young and doesn’t know how to communicate. I just hate that my patience is so thin right now.

Has this happened to any one else? I feel awful.