OP: you have a healthy BMI and you exercise well. Ignore those obsessed about body image and the lowest possible BMI.
It's disgusting how some women enjoy criticising the healthy bodies of other women, even when they can't see them. They are socialised to put other women down, to feel superior, instead of being supportive.
People of the same height and weight can have different frame size as well as muscle density and different fat distribution
Waist: height ratio is a much better measure than weight - lower body fat is far less important for health.
BMI 20 isn't healthier than BMI 24 for everyone.
Muscular women athletes with low BMI have to be careful they don't go below the essential body fat levels to maintain good health - there are a lot of EDs in athletes of all types and at all levels.
Women Olympic 2012 champions in strength events have much higher BMIs than runners - larger frames, not just muscle, e.g.
"Obese" BMI (30+)
Zhou Lulu (weight lifting) 42.8
Valerie Adams (shot put) 31.6
"Overweight" BMI (25-29.9)
Natalia Vorobieva (wrestling) 27.5
Sandra Perkovic (discus) 25.8
"Verging on Overweight" according to some posters 
Seimone Augustus (basketball) 24.3
Claressa Shields (boxing) 23.7
Lindsey Vonn (downhill skiing) 23.7
Tatyana Lysenko (hammer throw) 23.4
Most will have scraped off every last ounce of non-essential fat.
A normal women lifting heavy weights in the gym doesn't need to go to these extremes, so can be healthy weighing a lot more than than the Olympians.