pink- you can't self- diagnose.
It's simply no good trying to work out why you have this mass.
Plese try to be rational over this and face up to the facts: these are that it is unlikely to be cnacer, but given your family history you cannot afford to take a chance, as no woman can with a lump.
If it is benign, your mind will be put at rest, if it is not benign then even a day or so delay can make the outcome worse for you.
I am not sure if it is embarrassment at showing your lump or fear of what it migh t be that is stopping you making that appt NOW at the surgery- but neither is a good reason.
I am sorry Pink, but given what happened to your close relatives i simply cannot understand why you are dithering over getting this sorted.
Please just pick up the phone and make that appt.
Every single poster here has said the same thing - what else do you want us to say?