I think you will feel much better after next weeks appointment.  Either they will tall you it's nothing in which case you can forget about i(I think the majority of lumps seen at the breasts clinic turn out not to be cancerous)  Worst case scenario it does turn out to be cancerous they can sort out a plan of action which will help you feel in control   From my personal experience cancer is no longer the shock / horror nightmare it might have been 30 / 40 years ago.  There have been so many advancements in developing highly effective treatments also.  I hope this helps.  Let's us know how you get on.