Found a hard lump in my left breast that doesn't move and it hurts a little to add pressure to it. could it be something other than cancer?

Wrong question: Please forgive my frankness. The ONLY question that you should be asking is, "How soon can I get a tissue diagnosis?" I suspect at your age you have a benign fibroadenoma. But if you value you life and the feelings of the people who love you, get any dominant breast mass seen by your physician without delay.

Easily: In fact what you are describing is likely a cyst that may very well go away after you menstruate. If it persists you should see your physician and have an exam, possibly and aspiration of the cyst . This simple procedure can greatly decrease your discomfort. Obviously, its also important to have someone take your family and personal history and examine you. Decrease caffeine and ad Vit E

Statistically it: is unlikely to be cancer. Without an actual examination, I cannot give specific medical advice on your particular health, Fibrocystic disease is really common http://my.clevelandclinic.org/breast-center/patient-education/breast-lumps.aspx infection, other non-malignant lumps less common than fibrocystic but still all more common than cancer.

Breast US needed: While Fibrocystic breast disease is very common, any painful breast mass that is fixed (not freely moveable) should have further studies (ie. Breast Ultrasound, and diagnostic mammogram). Caffeine, Phentermine, and hormones (ie. your Birth control pills) can increase Fibrocystic changes and pain. However, when lumps are painful and immobile, further evaluation is indicated. See your PCM/GYN.

Needs evaluation: While it would be unlikely for someone your age to have breast cancer, ANY new palpable breast mass needs to be evaluated by your physician and she will likely recommend a breast ultrasound for further information. Listen to your body, and when something is new, different or worrisome - see your doctor. Good luck.