Getting nervous about having two kids

I’m beyond excited to be welcoming my boy in April, but I have a 2 year old daughter, and I’m struggling with how I’ll transition from one kid to two plus working full time as a teacher. It’s making me super nervous. Everything I read online pretty much describes having two children as a zoo, and it’s not reassuring. Just being pregnant has been a bit of a transition because I’m so tired all of the time. My daughter still likes to be held quite a bit and is still in diapers with slow progress towards toilet training. I’m just caught up in how the logistics will work. Any suggestions? Reassurances that this isn’t going to be a nightmare?