In laws, help?

Mayra • 🌻☀️🍕
I live with my in laws. Since I am 31 weeks pregnant. My bf and I have our own room. I help around the house, do laundry and keep the room clean. Every time my bf and I leave the house, we come back to find things moved in the room. My drawers are always open (as if someone was going through them). They come in and vacuum and "clean" the room the way THEY (in laws) want it. It seems like they have no respect for us. I know it's their house and they can do as they please. But, I keep things clean. Do they have the right to go through my stuff? I tried telling my bf that it annoys me so much, but he doesn't know how to tell his parents.