Going to Breast Center today(need advice)

Hello all,

Not sure if anyone can help me. I have had a steady growing lump since March 2011. I was breastfeeding when I found it. My GP wanted to wait till I was done breastfeeding to evaluate.

I had a mamogram that was negative and a ultrasound that was negative in Oct 2011. They noted some thickening on the outer region of the left breast. Which I was told then it was a normal part of my breast. So I would like a second opinion from a breast doctor. The original lump was no bigger than a lemon seed.

Now here are my symtoms today :

Dull ache in left breast

left breast feels full

noticed swelling under armpit

lump size of grape ,irregular shape with  a line of thickening vertical to top of breast with a dense spot, then more thickening towards nipple and including the areloa

Mild pain while breathing

What do I say if I have had a Negative mamogram and Negative ultrasound. Is it even possible? I would have been more assured if they at least found a cyst.

Is there anyone else who had this experience? 

I am 33 my paternal aunt had breast cancer at 55 and died at 63  

Thanks for the help in advance