Buy another case of beer from the store, leave your homebrew bottles in room temperature for another 2 or 3 weeks (ok, maybe buy 2 cases), then as suggested put one in the fridge, wait 2 days and see how much head you have... you will probably be ok. If not do it again.. I typically think that you need a month to bottle condition.
With less than 2 weeks in a bottle I don't think you gave it enough time to be able to come to a conclusion that it is your process..