Can a 57 year old woman have breast cancer if last mammogram was 1.5 years ago and normal? Never had an abnormal mammogram. What stage cancer?

Yes. The normal mammograms in the past won't protect you from future breast cancer. Also, mammograms are about 80% sensitive for detecting cancer, so 20% of cancers won't be seen. 1.5 years is enough time for a cancer to double in size 6 times. If you have a lump, see your doctor. If not, please resume your screening mammography.
Absolutely. Breast cancers arise from normal breast, and they can grow fast. And i can't tell you the stage of the cancer. Hopefully it is still contained. If you have an abnormal mammogram, you need to get a tissue diagnosis. It may be benign. If it's cancer, definitively treatment is much more likely than not to save your life. Do what you know you must.