>>535139341
Are you using her on Medium? Your problem is lacking acceleration skills, the other horses just have a better last spurt than you.
Stamina skills have a wit check to trigger, so 311 isn't really ideal, and BoFA can trigger too early/late.
Capping speed is also pretty important.
S on track/distance is a 5% boost on speed/power, which translates to +10.25% speed/power, a S turf for example will always have an extra ~120 speed over you, for example.