How can my g/f produce milk w/o being pregnant nor taking hormones? i only see her once a week, so there can't be constant sucking.

Prolactin: This is abnormal and can represent something very serious. She should never just sit at home and have this condition. Please encourage her to get to the doctor on Monday for testing.

See a doctor!: Hi. Is she having periods? The most likely explanation would be that she has breast milk and no periods due to a pituitary tumor that makes a hormone called prolactin (PRL). It's also possible, although less likely, that she's taking a medicine that elevates PRL (disregard if she takes no medicines). She needs to see her doctor for a good history, physical exam, and tests. Good luck!