Bren, this is where the tweaking comes in. I would caution you to not go below 10-12x your current body weight. Use that as a minimum in your case. 100 calories can make a huge difference when it comes to what works. At 1700 I'm hungry, at 1799 I'm happy.

BMR calculations are just that, calculations. You'd be as accurate if you called them a sophistocated guess. If you have a more active metabolism then you're going to need more energy.

One sure way of figuring out your calorie needs would be if you knew your maintenance levels. At what number can you eat and not gain fat? Take this number and subtract 500 calories - this gives you approx 1lb loss per week (approx of course). You can also calorie cycle (raising and lowering calories on a daily basis by a specific deficit with the net calorie count at the end of the week being the number that is your BMR - 500 divided by 7).

Calorie cycling helps to confuse the old body so it doesnt think "diet". Here are a few good links that can explain in better detail what I mean

ABCDE Diet
Muscle Media - ABCDE

HTH
Nat