Humbled and frustrated already.

Being flip with your instructor is not a good way to start!
Most people that I've seen with backing issues are control freaks, they have to continually tell the truck what to do, i.e. always turning the wheel. Basically a correction doesn't have much effect until the truck has move 8 or 10 following the correction.
You need to provide more detail about what your having trouble with.

 

You'll get it. First time I did a blind side back, I hit all the cones. Almost jack knifed it on the second attempt. Trailer position was all ### backwards. The thing is in the pickup you can see pretty much everything going on, and the trailer pivots at the back of the truck. In the truck there's a lot you cant see, use your mirrors, stick to your reference points and GOAL. The more you GOAL the better you picture the truck/trailer position in your minds eye if you will. Also the pivot point on a semi is right over your drive axles, so it's a tighter swing and you have more angles available to get the trailer in position. Just stick with it. And try to find a more helpful instructor.

 

You have to take into account that these trailers are slower to react to steering movements than say a boat trailer. I had the same problem the first day of maneuvers and the problem is I expected that trailer to start turning as soon as I turned the wheel and when it didn't I tried to compensate by giving it a little more. By the time I realized my mistake my trailer was jackknifed or in the wrong direction. The good thing is because of your backing experience, you already know which direction to turn the wheel to get that trailer to turn where you want it. For the offset try this turn pattern they taught us in school.

Right Offset (Starting in the left land and moving to the right lane):
Start off by turning the wheel 1 time to the left.
Back until you see the center of your landing gear.
Cut the wheel all the way to the right.
Back until your tractor comes back in line with your trailer.
Straight line back until the trailer tandem touches the center line between the two lanes.
Turn the wheel all the way to the right.
Back until you see the center of the landing gear again.
Now cut the wheel all the way back to the left.
Back until trailer is straight with tractor again.
At this point the combination vehicle should be lined up for a straight line back into the lane.
Straight line back it home.

If your school does parallel parking the routine is pretty much the same except without the straight line backing. I would write this turn pattern down and then stop along the way until you learn the turn pattern. Then eventually you can do the maneuver without braking at all.

 

your just used to short trailers, I bet u could back a pup like a champ. have faith in yourself there is plenty of drivers out here been driving for years and still cant back

 

Sounds like you're over confident. I also would venture to guess that you're turning the wheel more than you need to. I don't know what length trailer you are using but like the above said the trailer takes between 8-12 feet to react. When doing an offfset backing maneuver you shouldn't have to turn the wheel more than a 1/4 turn. The less you turn your wheel the easier it is to chase. Same goes for straight line backing. As for alley docking I hardly ever turn my wheel more than a half turn. That is all dependent on my set up. Don't use the throttle when backing. Idle only. Lot easier to control the trailer that way.

I've seen quite a few drivers struggle with backing because when they do a pull up they try to position the trailer where they want it. What works for me is keeping the wheels straight when I do a pull up. Try not to turn the direction you want the trailer to go. If you're alley docking and you're too far to the right pull straight ahead about 8-10 feet. When you start to back turn your steering wheel towards the problem side (right). Vice versa for the left side. Good luck

 

Backing a semi is very different than a boat trailer because the pivot point is directly over the drive axles instead of behind the rear bumper. I can back a 53' in any situation you put before me. I'm on vacation this week with the family in FL and yesterday I tried backing a 17' boat into the water with a minivan and I looked like a total noob. I tried and tried and kept getting more and more frustrated which made it way worse. Finally I had to hang my head in shame and let my dad back it in (he's not a truck driver). I guess what I'm trying to say is just keep practicing and soon it'll click. Don't worry too much that you can't get it on the first day. You're instructor probably saw that all you needed was a little trial and error to get the hang of it, which is the best way, for me anyway, to learn.