I've jst this minute read your posting, I jst want to let you know that I'm going through a similar situation as you. In my opinion it's very natural to worry about something like this. I found my first lump when i was 18 and had to wait 6 weeks for a appointment. During that waiting period i kinda was freaking out a little, but thankfully my results were positive. I'm 25 now and have had 12 lumps removed. (a reducing bra size totally sucks ) Infact i'm going for some more biopsy results tomorrow. What stops me from worrying about it though is having a chat to my close friends & family and, i'm also one off those people that like to make it a bit off a joke. That's my coping mechanisim i guess.
I would consider contacting your breast clinic appointment centre and ask for a sooner date. My hospital is good that way. And you might even get a nice receptionist on the phone.
I hope that everything goes well.