in your preseed.cfg under the ### Package selection you have not specified any package selections.
### Package selection
#tasksel tasksel/first multiselect standard
# If the desktop task is selected, install the kde and xfce desktops
# instead of the default gnome desktop.
#tasksel tasksel/desktop multiselect kde, xfce
#d-i tasksel/first multiselect
#tasksel tasksel/first multiselect
#tasksel tasksel/tasks multiselect
tasksel tasksel/first multiselect standard
I've commented your settings and added one line.