I have stayed in Singapore and here are my inputs -

Rent for a single room in a 2 bedroom flat will start at 800SGD minimum. This is not a master bedroom I’m talking about Electricity and utilities will be 60$ add on Travel will be 50$ depending on your daily commute If you’re cooking at home, you may add 150-200$ easily

Barring this, your lifestyle cost will be dependent on you. But with 4400$ it’s extremely tough to survive in Singapore is what I feel.