Really enjoy humanising posts like this - reminds me that doubt is normal.
As far as 42Floors, from the outside it certainly seems like they're killing it. I've been keeping my eye on them for a while, and have been impressed by both their app (a likeness can be drawn to Lovely in the residential space - both are awesome) and by how genuine they seem about taking a bunch of awesome people and having a crack at improving a massive outdated industry. If I thought I was a good match [I'm a PC-loving C# fan ;-)] I'd definitely consider working here.