What Causes Intermittent Periods With Heavy Clots?

I have been on the pill for 20 years. Only time I got off was to get pregnant for my children. I can't remember how my periods were before. Last month I was under a tremendous amt of stress and hardly had a period...only two days with a panty liner. I didn't start the next pack. I will be having my tubes tied next month and wanted to see how my body reacted. I went 10 days without any bleeding then started bleeding on the 11th day. The bleeding was more than normal with clot. Now I am on day 7, the last two days the bleeding was light..panty liner only. But today, it seems to have picked up with heavy mucus discharge and some small clots. I'm wondering if this is my hormones or could there be a possible hidden issue that I have that the pill masked. My gyno is saying 'wait and see' but I am concerned, especially since I plan to be off hormones completely in a month. I don't want to get my tubes tied if I'm going to be forced to take BC pills anyway to control my cycles.