So worried and anxious

Hi all, I am 21 years old and have had a small lump in my left breast since last May. I had 2 breast examinations but felt as though the doctors were quite unconcerned because of my age and told me it was nothing to worry about. I also have pain in both breasts, and used to have it really bad in my sternum, but that has improved. I have been told it may be related to my contraceptive pill. I went back to the doctors yesterday as I feel the lump is becoming slightly more prominent, but everytime I have gone I can never find it due to nerves and trying to be quick etc. My doctor told me she thinks I am feeling by rib bones underneath as I am slim build with small breasts, but my right breast doesnt feel like this and I am convinced its a lump because it sticks right out when i lie flat, it gets quite tender and sore around that area. Anyway she finally is referring me to a breast specialist for ‘peace of mind’. I know breast cancer is quite uncommon for my age but I just cannot stop worrying and cannot eat anything. The thing that worries me most is that if it is cancer that I’ve had it now for at least one year. I also know that its hard to detect in younger women, so thats making me panic even more and it could not even be that! Any advice would be greatly appreciated thank you.
Thank you for reading
Molly x

Molly u were so right to pursue this. Im sure you will be fine . Xx