Pregnant with a toddler: managed just fine, the times I felt tired we just chilled. I also worked full time up to the last weeks. I had a comfortable easy pregnancy.
Newborn with a toddler: 3 yr gap made it easier. I didn't have 2 in nappies, 2 on milk, ds1 was self sufficient being able to help himself to the fridge , change himself, feed himself and was completely toilet trained and he would quite happily play on his own. Ds1 was also a good sleeper so that made it easier too. The only thing was that the first 6 weeks of having a new brother, he played up a lot, perhaps a jealousy thing but it was short lived and all good thereafter.
I seriously found having a second child not much different than having the one. We are lucky our boys have been relatively easy.
I do have a Dh who is very helpful, supportive and hands on to.