I Am A 71 Y.o. Female. I Had Breast Cancer

I am a 71 y.o. female. I had breast cancer in 1999 with a modified radical mastectomy. I did not have followup oncology. I still have my uterus and ovaries. I've had "spotting" for several years and undergone 3 biopsies because the endometrium is 4 times as thick as it should be. But my OB/GYN has not done a hysterectomy. (I had a D&C in 2004). Now I am having daily bleeding, and passing mucous and clots. Mostly old dark blood, but some fresh red blood. I have an appt with my OB/GYN, but it isn't until Sept. Should I request an urgent examination?