All the conditioning and food and hydration may not be as important as your acclimatization status.
You did not mention your sleeping altitudes or days/nights spent at altitude beforehand. Some people need no time up high before Whitney, some one day/night or some need even more than that (with height varying per individual).
People have an absolute altitude ceiling. This could only be determined with multiple forays and usually would be to higher than Whitney. In other words, with acclimatization Whitney altitude is within most healthy people's altitude capability.
Here is a rule from the CDC written by well-respected high altitude expert Peter Hackett MD. This is a very general guide some people need more time than that.
Ascend gradually, if possible. Avoid going directly from low elevation to more than 9,000 ft (2,750 m) sleeping elevation in 1 day. Once above 9,000 ft (2,750 m), move sleeping elevation no higher than 1,600 ft (500 m) per day, and plan an extra day for acclimatization every 3,300 ft (1,000?m). [ie, if going higher than Whitney]
