D.C.
Hi Jenn, I did feel that way with my children, my oldest was a year and a half when I was pregnant and I had my second one shortly after my oldest turned two but she was still a baby to me. Still in pull ups and still staying at home with me. My first few fears did come true, I was overwhelmed and I didn't have help and I cried a bit but after I cried, I got to work. I didn't really have time to dwell on the fact that I didn't have help or that it was hard as hell.
You have to put both of them on a schedule for sleeping and eating and somehow take time for yourself when they are sleeping. I won't lie and say it won't be challenging but if you get some order about how to do things, it won't be as hard. If you have a calendar, put it on your frig and write down their feeding schedules and what you plan to cook and write down the nap schedule and what you plan to do once they are sleep even if that means sleeping yourself.
The thing is, the more you think about it, the more overwhelmed you will get because you don't know what to expect but that's with anything. Just know that it gets easier over time and see if there is anyone in your family who can help you out once or twice a week. I didn't have much help but one other thing I did was always took the baby with me whenever helping the older one.
It will get better once you have the baby trust me..... You will be just fine.