In general, if something flags up on screening / tests, you tend to hear sooner rather than later. My positive poo test resulted in call two days after submitting it, whereas my husband's multiple negative ones took longer. I don't know about mammograms, but I'd say no news is good news, although I can totally get how your health anxiety could convince you otherwise. However you could ring your GP and see if they have heard anything as results would also be logged with your surgery.