food quantity question

I have been feeding Tessie for about 4 weeks on Blue Buffalo Finiky Feast and at first she would gobble up the food and eat 1/2 cup everyday. After the 1st week she has now only been eating about a 1/4 cup a day. Is she just sick of the food or do you think she just isn't hungry? She is drinking plenty of water and still enjoys her treat in the morning and at night (greenies). I just want to make sure 1/4 a day is enough.
She is fed wet food about 3 times a week. I do not have the money to feed her it every day.
Thanks!

Some questions:

What were you feeding before blue buffalo? How long do you leave dry food out before throwing it away and putting down a clean bowl?

BB does not have artificial preservative so it will go rancid even more quickly than a junky food.

I recommend you schedule feed, or at least put only 1/4 cup at a time in her bowl, and use a fresh bowl and fresh food for the next meal. Never put fresh food over old, never leave uneaten dry food to sit more than 8 hours, throw it away, and put down fresh and a fresh bowl.

Has she lost weight?

I was feeding her Wilderness before but the vet recommended I switch her food with some grain in it.
She has lost a little weight but she needs too was at 12lbs. The vet wants her down to 9lbs she is currently at 11lbs.
I have been putting 1/2 in the morning before I leave for work and emptying the old food out the next morning. I will go back to feeding her 1/4 twice a day and see if that helps.
It does get hot in my bedroom but I have the unused food in an airtight container, do you think the food could be going bad because of the heat?
Thanks!