Tamoxifen and weight gain

It's an interesting one, I was on tamoxifen for 4yrs pre menopause at 43-47 years of age before I had a recurrence. I didn't have any issues with weight gain or side effects that were super noticeable. However at my recurrence at 47, Chemo threw me into an unnatural menopause and then went onto Arimidex, whoa! heaps of side effects so a year later I was switched to Aromasin...hmmm yeah no different, Ive just learnt to live with it I think. Though...I put on weight through treatment like 7kg and 2yrs on cannot shift it through diet or exercise. So I'm wondering now the weight is a combination of things, its firstly chemo related for me, menopause and then Aromasin, all together make it near impossible. I admit its something that really annoys me.. Melinda xo