I have the same thing. I was referred under the 2 week pathway to the breast clinic. I was scanned and everything was normal. No idea what it actually is, but they said all they could see was breast tissue and nothing abnormal. 

Hope all goes well.

I don't understand why the wait for you is 12 weeks. I suppose of you can afford it, it's worth doing to put your mind at rest. I hope it's nothing for you too.