Leakage w/o being full?

Amanda • ♐️ // 23 // feminist 🚹 = 🚺 // Hufflepuff 💛// pro choice // 🚫No baby dust, please!🚫 // 💕8-27-16💕

I put my cup in the day before my period and take it out when I need to. No leaks. I keep doing this, and it’s usually only about half full. Around day 3 of my period I’ll notice small stains in my panties. I know my cup isn’t broken or otherwise defective, and I know it’s the right size for me. Does anyone know why this is happening?