Weight loss isn't linear. Even if you are a perfect automaton, 100% constant in every single choice you make, what shows up on the scale will STILL vary. If you know you've been making good choices and are sure you've created a deficit, it will show up -- eventually.
That said, high stress can absolutely impact your weight loss. Google cortisol, stress, and weight if you want nitty gritty. The month before we closed on our house earlier this year wasn't pretty.
My advice is to take care of yourself - try to bring your stress level down - and don't worry about small scale fluctuations.