12% body fat is actually so low for a female that it's considered unhealthy. Healthy body fat levels for a female are 18-25%.
How do you feel at 12% body fat? Most women would loose their menstrual cycle and start to loose their hair at such a low body fat.
If I was you personally, I would hold off on the winstrol cycle and instead, focus on lean bulking. Some curves on a woman look good.
Winstrol is one of the worst steroids for hair loss. Using winstrol with how low your body fat percentage already is - you will loose hair like crazy on your cycle.