Calculating optimal calorie intake

I was reading 'Burn the Fat, Feed the Muscle' last night, and it's made me realise that, like I'd imagine a lot of people, I have no idea how many calories I consume, much less how many I should be consuming.
The average TDEE for men is 2800; but I'm short, and have a desk job, so probably burn a lot less. It's time for some calculations.

On Wednesday I took a new set of measurements; I've gone up to 72kg, but down to 18.8% body fat - which means I've lost 0.3kg fat and gained 0.6kg lean body mass since last Monday. Which is, if not a blip, a sign of excellent progress

Using the Harris-Benedict formula (for men) gives me a BMR of:

66.5 + (13.75 × [weight in kg]) + (5.003 × [height in cm]) - (6.775 × [age])
= 66.5 + 13.75 × 72.0 + 5.003 × 173 - 6.775 × 29
= 1725.544

Using the Katch-McArdle formula gives me a BMR of:

370 + (21.6 × [lean mass in kg])
= 370 + 21.6 × 58.5
= 1633.6

That's quite a difference already.
Converting that into a TDEE using EXRX's calculator (estimated 9 hours rest, 13 hours very light activity, 2 hours light activity - commuting and cleaning my flat) gives 2409 and 2279 calories. Using the flat 1.2 multiplier for a desk job from ''Burn the Fat, Feed the Muscle' gives 2071 and 1960 calories.

This gives a total range of 1960 - 2409 calories, i.e. 469 calories. I'm thus going to calculate my ideal calorie intake for weight loss it cautiously, and aim for the lower recommended percentage drop (15%) against an average of the above figures (2180 calories), i.e. 1853 calories.
Should my actual TDEE turn out to be close to the lower end of that scale, it represents a 5.6% / 109 calorie drop; if the higher end of the scale, a 23.1% / 556 calorie drop. So even if the initial estimate is wrong, it shouldn't be damagingly so.

I'm going to start with five meals a day, and decide whether to move to six once I'm into a routine. This means each meal should be approximately 370.6 calories, 436 on 'cheat' days (every fourth day, to reset my metabolism). Ideally, breakfast should be 100 calories more, and dinner 100 less, but again, that can wait.