Although I went into my driver's test with only 6 hours total driving(the driver's ed my parents wouldn't help me practice at all after before my test) and passed it first try practice makes perfect. Instead of being worried you could've bought 2 cones and practiced until you were so pro it would be laughable to even worry about it. Maybe if you don't pass you can think in those terms for the 2nd try.
I've been driving 7 years and done lots of landscaping and construction in busy cities like LA and portland and I can throw a 1 ton with a dump kit like this:
into a spot between 2 cars in like 5 seconds flat I fly right in and you can't even see behind the truck with a dump kit but I'm good at calculating my distance from cars by taking a mental image of them as I pass them up before I go in reverse and I just know where they are without seeing them. I'm also pretty good at backing up 30 foot trailers around bending roads at 80 mph(harder than it sounds)