Fuel Burn Question

[turbojetfan 8]

The other week, I ended up doing a flight in the A320 from Boston MA, to San Diego CA. I went to the (old) fuel planner and started with 0 pax and 0kgs of cargo. I then added max fuel and brought the passanger load to about 3/4 and the cargo to 2000kg. My planned route ened up being around 2250nm and headwinds were relatively moderate probably averaging around 50 or 60 knots with the initial segment from the northeast United States having higher and once I got past lake Michigan, they became more of a crosswing and decreased significantly. Anyway, despite having better than usual headwinds and flying at FL340 and then stepping up to FL360, I landed in San Diego with around 0.6kg of fuel total remaining.

Now, I didn't really track or watch the actual inflight fuel burn but at least according to data from Airbus's website, this should be well within the maximum 3,200nm range for this bird at MTOW and I was only about 75% of that. MY flight time was probably abour 5h20m and I've seen this route on flightaware last over 6h so it has to be possible.

Is there any way that either the fuel burn is off or at least a way that I could tweak it so that I'm not coasting in on fumes?

Thanks,