Lymph node in boob

Hi,

 

im waiting to be seen by the breast cancer clinic on Thursday after I noticed a small lump in my boob, the GP thinks it's a lymph node but wants to get it checked as I didn't have any reason for the lymph node to be up. I'm 24 and have a history of breast cancer in my family, I was seen back in February by them after having pain in my left armpit but they didn't scan me as they didn't feel anything suspicious. Has anyone else experienced a Lymph node in there boob and it turned out to be nothing? Ive done well to stay calm about it but as the appointment is getting closer I'm starting to panic. Any help would be great, thank you!