I would speak directly with the mail carrier, he/she would be the only person that could tell you if the package was delivered to YOUR house. Maybe someone walked off with it.

I have a similiar problem, my mailbox is ganged with four other boxes close to a fairly busy street, and about 100 yards from my house, and if a package won't fit, she'll sometimes leave it right next to the box, in plain sight (she did this with the CAO set I got from you, Andrew, boy, was I PISSED about THAT!). I keep a cooler out on my porch when I'm expecting larger boxes, but she's too lazy to drive back there, I guess.