Image cropping.

There are 3 main reasons for images submitted for printing getting cropped.

1. "Spill"
The printing process projects a slightly larger image than the size of the paper that it is printed on. This is called "spill". It is usually around 1%. In other words, if your image is 2000x2500 pixels, there will be a loss of up to 20 pixels on the short side and up to 25 pixels on the long side. This can be important if there is critical detail close to the edge of the image or if there is a border around the print. If in doubt, get a test print made.
Note, there reason for the spill is to prevent white borders if the paper moves during the tracking through the printer.

2. "Incorrect image to print ratios"
All of our layouts are designed to fill the print with the image to the longest side. If you have an 8x10in image and order an 8x12in print, the image will be enlarged to make the 10in side 12in. Consequently the projected image now becomes 9.6x12in. When printed on an 8x12 sheet, 1.6in will be lost from the shorter side.
It is suggested that print sizes be ordered in the same ratio as the camera file unless cropping is done when sizing the image.

3. Using rounded metric measurements instead of Imperial measurements.
Street's use Kodak photographic materials which are supplied in Imperial sizes i.e 5 inch paper is 5 inches wide. Because of the use of Mertic measurements in Australia, we are required to give these measurements also in metric which we usually round to the nearest cm. eg 5 inches becomes 13cm. In fact, 5 inches is 12.7 cm. If you make your image 13 cm wide you will lose 3mm.
Hint. Set Photoshop/edit/preferences/units and rulers/units/rulers to "inches"