I would think that this persistent nipple discharge should be evaluated by a Breast Specialist.I don't think that it has anything to do with breast cancer but rather a benign breast condition,since it's happening bilaterally.Avoid squeezing your nipples,because you are actually making the discharge persist.
From what you describe it sounds like Mammary Duct Ectasia Symptoms, that may be caused by infection or inflammation of a milk ducts in the breast, near the nipple, causing green,blue brown or black discharge, that may also including a breast lump under the nipple.
This problem can be treated with antibiotics and non-steroidal anti-inflammatory medications or even surgery to remove the abnormal duct.
I hope you'll get this problem resolved soon,once you consult a Breast Specialist and start treatment that he/she recommends.
All the best to you....