What Causes Weight Gain Inspite Of Being On Estrace?

I have been on estrace for 10 years and all of a sudden (so it seems), I am experiencing weight gain. I am thinking of taking the estrace only every second night. The only other new meds I am on is twynsta for blood pressure and nowhere does it say that this med will cause weight gain. I need to find out what is causing the weight gain and make it stop. I had a hysterectomy when I was thirty two however I was left with one ovary so did not experience menopause until the age of 52. I am now 67.