I would agree with your nurse, the picture you provided does not show anything to be concerned about. :)
http://i68.photobucket.com/albums/i38/tdmdxc/Photo12.jpg
This is the picture of my tongue, my school nurse said it looks normal and is not thrush, maybe just a little white because of dehydration, excessive drinking, etc. Does this look like thrush?
Oral thrush is very possible, classic white layer that can be whiped off. Check in with a dentist to get you some antifungals.
from looking at my tongue it is actually white all over but more in the middle and back. If i could make an anology, i would say there is white grass/hair growing on my tongue, and when I scrape it off it just gets shorter, as if i was mowing the lawn or shaving my head. There is no bleeding, just shortening of the white stuff. Is this oral thrush?