If the area is larger than 5x12, it is seamed. Sheet goods are not, and never have been made larger than 5x12, at least not in my 30 + yrs of installing laminate. If I understand the layout, you have a corner sink. When I have to a seam in a top with a corner sink, and requiring a seam it is placed in the sink line, off one of the back corners, and at the front of the sink. The back seam is off the corner because it is the shortest distance, and the same for the front. I have installed seams that could not be seen, and that is what I try to do always. Usually, if you can't see the seam, you can feel it. Things to help with seaming is always paying attention to the direction of the pattern, (no quarter turning), and also pattern matching.