I second @ zoffiel's advice to contact a breast care nurse.
I didn't use mine enough and her advice was invaluable. They are very knowledgable and can help calm the panic.
I first found my lump in early December and did not have an op until 19th January. That was lumpectomy. I have since had the breast removed on 3rd August, but I had chemo in between.
I understand your concern, it was mine too over Christmas, wondering what the hell the cancer was doing while I had to wait.
How fast it progresses depends on what grade it is, but I was assured that a few weeks would not matter. Did it matter? I don't know.
I know I got in one hell of a state early on if anything was delayed, if an appointment ran late, or someone did not get back to me about making an appointment when I was waiting for a phone call.
I ended up having to take Valium for appointments, scans, tests and on days I was making appointments, and I am not a Valium type person. Cancer does your head in!
I did find that my specialists moved quickly when they needed to.
If they said surgery or chemo had to be within a 6 week window of the previous treatment, it was.
If I was concerned about the length of time I said so too.
Ask questions, be your own advocate and tell them how you are feeling, and what your worry is.