Suggest Ways To Lose Weight When Treating Stage-3B Rectal Cancer

I had stage 3b rectal cancer diagnosed February 28th 2013, while 6 months pregnant. Did 6 months of chemo and had a lower interior resection October 2nd 2013. I gained 70 pounds. I still can't lose 30 of it. No matter what I do. I get my period 2 times a month. Got. My thyroid tested they said it was in normal range. Any thoughts maybe something else can be wrong.