No privacy from In-Laws

I'm 28 weeks. I live in a duplex and my in laws just moved in next door. I was kind of excited about the move as I would have help when the baby comes, etc. I have quickly come to regret this! They never lock their door and so my DH tells me not to lock ours either. Ok so no biggy, BUT my mom and dad in law walk in and out of our home all day like we live together. No knocking, no warning, no consideration. Just swing open my door and walk in. Mom in law comes and sits and watches tv or whatevr and on top of that she makes plans for what "we" are gonna do next day or next week without asking if I'm free. Like she'll be like, ok so 2maro We'll go to the grocery store.... Etc.. I wanna die I'm such a private person and this is causing me way too much stress. I told my hubby that I feel like I no longer have any privacy And he said, ok when u need some you time just lock the door. But when I lock the door he says what r u locking my folks out now? What do u guys think? Am I being hormonal or this is really too much? I mean my in laws are good people just very controlling I think. How can I change things without coming out rude or disrespectful?