Leaving on a Jet Plane

Not quite yet, but soon enough. My sister is home from the hospital, BIL is back to work, and I've had a week and a half of caring for my nephew nearly all day, every day (thankfully, his father takes sleep-time). I've learned2 things.
1. Working from home is ridiculously difficult with a toddler (they get into everything and need constant attention - possibly do-able with an infant or an older child who was better able to self entertain, but not a child that you have to keep out of the electrical sockets and such.
and
2. I *require* a LOT of personal time, alone time, adult time.

I don't know why this would be different in relation to a baby as opposed to adults - I don't dig being around other adults ll the time either. In fact, unless I get ample alone time, I get pretty fussy. This alone time has to be outside of work. Free, alone time. I've noticed that, even though I don't spend that much time with F during the week, I still need some time to myself when I am not working. Even if we are only together for a few hours. If I am working the rest of the time - I need non-F time.
While F can find other ways to entertain himself for a few hours on an evening or a Sunday afternoon, babies cannot. No, babies want to (have to) go everywhere with you - even to the shower and the bathroom. Out of the last 14 showers I have taken, 11 have been with my nephew. He has to get clean; I have to get clean and I can't leave him alone for long.
Thankfully - my nephew is a fantastic baby. He entertains himself exceedingly well for a 15 month old and can play for hours, checking back with me every 30 minutes or so for a quick cuddle or a kiss of reassurance. I can run to the bathroom by myself; run upstairs quickly, etc. No problem (living room is baby-gated and baby-proof).
But - what if I got a 'high needs' baby? My father in law indicates that F didn't sleep through the night until he was a year old. When I say "not sleep through the night", I mean they had to walk the house with him all night, every night to get the kid to sleep. The minute they put him in his crib - he would immediately scream and continue until they picked him up and resumed walking the house with him. F has posited some theories as to why he is an only child - but I'm pretty certain this it the reason, and I don't blame them one bit. In fact, I don't know that it would have been wrong to give him up for adoption.
My mom has told me many a tale about how colicky I was and how I screamed, etc. BUT she went on the have 2 more kids, so I don't really put a lot of stock in that.
What if I got a baby like F?
That question gives me significant pause...