breast cancer symptoms?

So my left breast has been achy for about 2 months now. I went to my doc and she did an exam and didn’t find any lumps. She thought maybe it was my underwire in my bra. Which I never really thought it was because it aches all over, not just underneath. But I tried switching bras just to rule it out. Nothing changed. Just wondering if you guys have any advice? I’m a little worried that it’s cancer but at the same time I’m trying not to freak out because my doc didn’t think it was. No other changes in the breast.