Any tips?

Princess

Hi everyone a few days ago I adopted a tan and white domestic shorthair named toby shes so soft and fat shes a sweetheart that wants a lot of attention which is understandable she was abandoned outside my friends home he tried to take her in but his older cat didnt get along and toby had to be isolated in the basement of his house which I dont think is good for any animal. He barely was able to spend time with her cuz he worked a lot so when I got my own place I offered to take her in. She's really skittish and won't eat or use the bathroom unless I'm there which isn't always possible she doesn't sleep much and meows all night which keeps me up. I've tried calming treats sprays even a calming collar which she somehow managed to take off.i want her to feel comfortable and to relax at night but idk what else to do sorry my post is long but can anyone help? Thank you 😊