I know it's frustrating, but congrats on the loss!! You lost about 1/2 pound! As others have said, your period can contribute to water weight gain, but then, so can so many things!
Let me assure you that if you continue to lose weight you will have weeks where you do everything right and either maintain or even GAIN weight. Our bodies are complex and weight loss is not linear.
So, congrats on your loss and just keep plugging away!!
My 5 C's of healthy living: Commitment to conscious control, with the understanding that choices have consequences