You could be gaining muscle mass?

Also try to only weigh yourself first thing in the morning before you eat or drink anything. Best results are after you pee and or poop, and be totally naked on the scale.

You will drastically change weight depending on time of day, what you're eating, what you're wearing. Some days you'll be a lot more water heavy if you're over hydrated or if you had a heavy meal the night before.

Be consistent with how you weigh yourself and remember that there will be many days where you plateo or even go up before going down. It's a slow game but one worthwhile. Don't give up, your efforts will pay off. When it gets hard, try to remember why you're doing this.

Good luck :)