I wanted to post my symptoms in the hope it might help others.  I'm 29 years old and 2 months ago I felt quite a large lump in my right breast (inner, lower quadrant) it was hard and immobile.  My right breast has been larger than my left breast for a number of years...my right armpit has also been thicker than my left since as long as I can remember too.  But alarm bells went off in my mind thinking I had breast cancer and that I had it for a number of years and a lump was only showing up now. Apart from that no other symptoms.  Went to GP and she done a physical breast exam.  She felt the lump, which feels like a marble and said to me "oh is that it?"... she told me she had no concerns and that it felt like gristle but would refer me to the breast clinic for an ultrasound.  
 

Fast forward to 3 days before my appt at the breast clinic and I start feeling about my breasts and armpits (anxiety kicking in) Trying to FIND swollen lymphnodes after reading about a million different articles that swollen lymphnodes were a sign of cancer.  Covering every inch of my breasts and armpits... found LOTS of pea shaped lymphodes in right armpit, in auxiliary section (pain in right armpit too radiating down arm) and a few in the left armpit.  I literally looked at myself in the mirror and thought this was it. I had Breast cancer. Leading up to my appt date I could barely eat or sleep.  But I also became more calm and was in an "acceptance" phase.

Went to Breast clinic and had a physical examination 
with breast consultant.  She felt both breasts and then felt the lump... she wasn't concerned and said it was just breast tissue, our breasts are lumpy, one breast can be lumpier than the other too. I said to her about my lymphnodes and she said what I was feeling was "normal". She could tell i was still concerned (I mean Dr. Google had told me I had Breast cancer) so sent me for an ultra sound which came back all clear.. even showed me my lymphnodes were NOT swollen and were normal.

The best thing I did was go to that referral. I have major health anxiety and put off doctor appointments even when I'm ill...but please don't hold off getting yourself checked out if you have symptoms.

For anyone who's reading this, I've been in the same position and the anxiety is unbearable but this is the worst part, the not knowing... Being there at the appointment getting checked is easy and not scary as what you are probably imagining. Sending lots of love