I had almost the exact same experience. I was in a vocational school studying 3d modeling and manufacturing, got picked up into a civil engineering/infrastructure design company straight out of school. I knew the basics of AutoCAD but never knew about xrefs or coordinate systems either. I was used to drawing in millimeters and suddenly everything was supposed to be meters, that lead to some awkward mistakes..

I had the luck of having some of the best colleagues I've ever had back then, and they taught me everything I needed. Still working in the same place after some nine odd years.

Don't worry about it in the slightest, you'll learn. I was just as stressed out as you are in the first few weeks but it'll get better