Be careful, you have to provide a screenshot at one of the specified marks:
The screenshot was originally asked at Mars level, but because Mars orbit is elliptic now it's not reliable anymore, that's why we now give the liberation speed at specific distances.
You'd have to go back to your game, time-warp and take a screenshot at 15.000.000 km, but given your speed I'm practically sure it's not good: your speed is 6320 m/s at roughly 12.500.000 km, and you would need to be above 6311 at 15.000.000.
Don't hesitate to add fuel to your rocket, you're still below the 265 tons limit by more than 15 tons.