My cat will not lose weight no matter what and now i’m worried her diet isn’t enough for her

Hi yall I have a cat named Pumpkin. She came to us 2 and half years ago. She was one of my sisters 6 cats and was 26 pounds (believe it or not she was the 2nd smallest 😋) Me and my boyfriend agreed to foster her and one of her siblings while they lost weight and once they started losing weight we planned to find them homes.

Pumpkin did not lose an ounce for 2 years. She is just our cat now. Her brother passed away soon after we took them in so she’s a solo cat. We went to vet and did everything right. We slowly deceased her food, increased playtime. I started talking her with for walks and jogs (she is so fast for something so fat). But she was still sitting pretty at 25 pounds.

The only time she lost weight was the first week with us where she lost a pound. She’s been tested for every medical disorder known to cat and man and she’s literally fine 😭 She has no disease or anything. Her thyroid and blood have all been checked.

She is losing weight now, but I worry because her regime is harsh and she seems miserable. I walk her around 2-3 miles a day or jog for about 20 minutes(I track this so I know it’s true) she usually gets two 15 minutes plays session a day.

She only gets 110 calories a day of purina weight loss mixed with soup and nothing else . (the soup thing is weird but is vet approved and the only way she eats without throwing up, even water won’t do it it’s low sodium) This has given us some progress and she’s been able to lose a pound this month after 2 years of nothing.

My vet is the only one in my area I can afford (tried all other options none work without me having to go into debt and I refuse to do that lol) He’s never believed me and just things were feeding the cat too much. He doesn’t believe she’s eating as little as she is so he really isn’t any help.

Before this she was too fat to jump or really be a cat but know that she’s losing weight she doesn’t do anything anymore besides cry for food. Whenever we are home she cries, I don’t even know when she sleeps and she has no energy. I have to force her to go on walks and she fights me the whole time. It’s to the point we’re were considering just giving her to a rescue or someone who specializes in cat weight loss. I’m worried about not feeding her enough but her size is so bad for her health I don’t want to increase her food either. Even at 150 a day she wasn’t losing.

Please for the love of God yes I am 100% confident on her intake we have cameras in the house and literally put a go pro on a collar to see what she did all day- she only eats what we feed her. All human food is bikelocked.

Please help, is she gonna be okay? She hasn’t seemed lethargic just annoyed. She’s 23.88 pounds now. (Sorry for any typos or grammar mistakes. I typed this quick)