Large lump found in right breast

Good evening , 

last Thursday while in the shower I discovered large 5/6 cm lump in my right breast. Friday morning I called my GP and was examined that afternoon. My GP found the lump and agreed it was large. It seem to come out of nowhere. My GP has sent urgent referral due to the size and my age (41). I'm told I should here within the next 2 weeks. I'm trying to not worry until I know what this lump is but it's in the back of my mind constantly. Obviously there will be people in this chat that has maybe been through similar experience. Any advice would be much appreciated. I'm sure this next couple of weeks will seem like a lifetime while I wait. 
 

kind regards