missing periods

Jane
So my last period was back on November the 3rd and was a normal 4 day period and I haven't had one since.
The first few weeks I kept getting cramps thinking af wud come but never did tons of negative hpt and negative bloods two weeks ago.
I started getting sore boobs Monday so I'm hoping it shows up soon. The doctor has just told me to wait it out, I don't have pcos or anything like that. I've never missed a period unless pregnant, so why all of a sudden miss two in a row? I've not had any weight changes or been stressed 😩