when i first started doing anemones i had 3 die off as well
now i have alot and havent killed any in well over 2 years, it looks good its expanding and its trunk isnt streched way out so that means its getting the light it needs, when a anemone wants more light it will move higher in the tank, and strach WAY up as high as it can and expand alot larger then it should to try and get the light it needs, yours in on the bottum so it isnt looking for more light