L.M.
I agree with the advice to get time to yourself (go to bookstore, Starbucks, etc.), as well as the suggestions to consider finding a therapist to help you vent. Raising a toddler is hard! And, while being pregnant with another baby, yow! Lots of hormones and fatigue and challenges there. So, know that you're not failing somehow (or that your current state of mind is permanent) - you're doing the best you can.
Having said that, some of the symptoms you described sounded like signs of mild depression. I'm going to recommend a book called, "The Chemistry of Joy." It's about Western and Eastern methods of diagnosing and treating depressive disorders. I recommend it because you're experiencing many "triggers" for depression right now, and the book explains how to tell if you're dealing with an episode, as well as medication (which I'm not advocating for while you're pregnant) and non-medication ways to address it (fish oil capsules, vitamin B, types of foods to eat/not eat, types of exercise, etc.). Many of its non-medication suggestions are things you can incorporate into your life, even while pregnant (with your midwife or doctor's okay).
Wishing you peace of mind and fortitude for that toddler! :)