Kristie, I commend you for being so aware and proactive when it comes to your breast health.  I wish others were so aware! In my opinion, I think that at your age it's likely typical hormonal changes - as they do tend to cause tenderness of the breasts, and it's certainly a possibility that the hormones can be causing cysts that will come and go with your cycle and hormones - if you have dense breast tissue it could be fibrocystic tissue....there are so many types of benign lumps that it could be.  Cancer would be extremely rare for your age, even with your family history.  Sometimes genetics has nothing to do with it - I've had breast cancer twice now by age 34,  I was the first in my family to have cancer and I'm not a gene carrier either.  I swear sometimes it's like there's no rhyme or reason to it. Like Phyllis suggested, talk with someone that you feel comfortable with.  Monitor the lump over the next few weeks and if it doesn't go away, or if it gets larger or changes shape then definitley see a doctor.  There is no reason at all for you to worry or stress over it, especially when you can get an ultrasound done and know if it's abnormal and should proceed with some type of biopsy - but you really shouldn't be worrying yourself sick over it.  I'm sure it will all turn out to be ok! Good luck to you! Angi