Congratulations : )
My parents had 11 children, and I have a brother and sister 13 months apart :-/ Mom did it somehow, and in retrospect I have to say there was probably some of the least sibling rivalry between these two than any of the rest of the clan...possibly because they were so close in age. The only ones who got along better were my twin brothers.
I guess i'm kind of a Pollyanna (wow, am I dating myself!) in that I try to embrace whatever comes at me as something to be dealt with, not feared. I say look on the positive side and do what needs to be done...when you're sick you may need to put your toddler to play in the pack n play or gated area and be sick, nap when your toddler does, once the baby arrives practice shortcuts to cleaning house, making meals, etc., so you have time to spend with both children, trips to the supermarket, doctor, park, etc., can be for both children at once. Start preparing your toddler now for the new sibling so it's not a shock, include them as a helper when the baby arrives, and roll with it all, don't fight it.
I know you have more pressing things to think about right now but if you're planning to transition your older child to a toddler/twin bed do it a couple of months before the new baby arrives so they are adjusted, or several months after the birth, otherwise they may see the move as something they HAVE to do because of the baby and resist/refuse the move and dislike the baby. And, this is waaaaay in the future so just catalog it, but wait to potty train your older child until the new sibling is at least 6 months old, otherwise you will more than likely face potty training regression, it is common and happens even in the most well-adjusted children.
You're family is growing, that's a blessing, congrats again!!