Hard immobile lump on rib bra line

I noticed my right breast more tender than my left months and months ago when my baby rested his head on my chest. I’ve now had a stiff shoulder and neck pain which radiates down my chest wall and into my armpit. The pain was particular uncomfortable and I was feeling around and felt a hard immobile smooth lump on my rib under my right breast. 

I expected the GP to say it was a kink or nobble on my home but she said it was a prominent lump in my breast tissue and has referred me within 2 weeks to a breast clinic. 

my baby turns 1 tomorrow and all I can think about is whether it’s the only birthday I will get to celebrate with him. I’m going out of my mind with worry and don’t know how I will get through the next few weeks as I have heard that results take a while after the scans and biopsies too. Has anyone had the same and it turned out not to be cancer? I’m clinging onto any hope that I can. The fact that it is hard and immobile isn’t giving me much reassurance. I’m 33, no family history of breast cancer, I don’t smoke, I couldn’t breastfeed.