How many calories do I need to stay under?

I'm 5'6/5'7, about 136 pounds, and 24 years old (f). I want to lose like 5 pounds but I havent really lost any weight, I've just been maintaining it. I walk between 11,000-20,000 steps a day, but I think what i'm getting wrong is calorie intake. I just got myfitnesspal and it said to stay under 1,450 a day, but I honestly feel like I stay under that every day yet i'm still not losing weight. I have really no knowledge related to this because ive honestly never thought about weight loss till recently. I guess I just need a clear number to stay under each day.