I've suffered from a similar problem since my teens due polycistic ovaries and a hormone imbalance (which are probably linked). I have no other symptoms, my periods are normal and I'm not pregnant. I'm not an expert but a simple blood test by your GP can usually confirm the diagnosis as far as I know. In the meantime try electrolosis as its better than plucking, it has a more permanat effect, and if you keep plucking those little white numbers they may start to darken. It's a bit expensive but some of the home treatment kits can be quite effective and are pretty cheap to buy.