Does Taking Estrogen Mtest Amn Cause Weight Gain?

hi ....just a week ago i started taking estrogenmtes amn...and have some weight gain...i am pretty thin and always worry about my weight i have never struggled with weight gain and it is making me very nervous...should this continue what do you recommend...just for a breif history....i had a complety hystgerectomy in 2005 and had not been on any medication what so ever.....hopefully this will help with hot flashes and mood swings galore....