... because the gudie I followed was for just the same lcd.
I must have missed the place where you told us about this guide. Surely you don't mean the 'Hello World' example because that display obviously has the pins in a different location.
Is it true that the first pin to the left is my number 15 and next is 16?
According to your datasheet (page 2) the end pin is the backlight anode (+) and the one next to pin 1 is the backlight cathode (-).
I bet that when you get it working you are also going to find that you have been looking at your LCD upside-down. The LCD's with the row of pins at the top left seem to universally have the pins as you expected, pin 1 nearest the edge of the board and pin 14 (or 16) nearest the center. The LCD's with the row of pins at the bottom left usually have a different layout, and they are not all the same.
Now that I think about it I have not yet run into a display with the pins at the upper right, so yours may be a new (to me) variety.
Don