WHOA, ChunkyChic, yes that is very low
Again, RockinRobin is right. (thank goodness for the pros here) Those calculators will never be 100% accurate. It can give you a jumping off point, but that is about it. I bet even if you went to Tom Venuto himself who REALLY advocates calorie cycling, he wouldn't be able to give you an exact figure.
So we know for a fact that you cannot DROP your calories anymore. There is nowhere else to go except up. Try the 13-1600 if that is where you feel comfortable. I go up to 1800 on two days and it doesn't affect my weight loss at all. In fact, by looking at my logs I keep, I would say I lose the MOST on average on the days following the increases.