Hello I'm 19 Years Old And For The Past 3

Hello I'm 19 years old and for the past 3 month I've been having issues with only my left breast. I have an enlarged axillary lymph node and I've been prescribed many different types of antibiotics to try and shrink it. Lately my left breast has been leaking white and clear fluid, and when I come close to my menstrual cycle I obtain a hard lump/knot in my breast. For the the past 3 months my primary care doctors have been stumped. I'm prescribed over 1 gram of antibiotics every two weeks because they think I have an infection but in the end I dont. They've run prolactin tests, ultrasounds, hormonal, CBC's and many more. All of my tests came up  crystal clear. They can't figure out what's wrong with me and come to the conclusion that it may be abnormal to some people but it's normal for me. I need advice on what my condition could be and what future steps I should take to seek help.