Hormonal changes may cause you to be lactating a bit, even if you're not pregnant. Even though its a bother, asking a doctor is always a good idea, if you're not embarrassed. You should also research symptoms of PCOS online, might find answers there.
Hyperprolactemia. This is an excess of prolactin produced in the brain. Prolactin tells your breasts to make milk.
It may be related to your PCOS or you may have a benign tumor on your pituitary gland.
You need to see a doctor.
i have something similar, although my bra isn't wet. i have discovered that my white bras all seem to have quarter-sized stains on them...just dirty spots on the inside of my bra cups. it's bizarre.