Pregnant & living with bf's parents

So long story short my boyfriend and I of 6 years are having an unplanned pregnancy (IUD failed). Both sides of our family are extremely supportive & have been very helpful to us. We were both in college in Ohio, had full time jobs, and living on our own prior to becoming pregnant. I also had/have a pre existing condition before becoming pregnant that requires me to have many accommodations at work and college. My pregnancy has only heightened my condition making both impossible. So I had to quit my job, and take a break from school until the baby is born. 
Because of this we couldn't afford to live on our own, so my boyfriends parents had us come live with them our in California so that we could live rent free and my boyfriend can focus on school more. 
Other than natural living differences, it's become very stressful. They have 3 dogs that shed horribly, and they are not very good at cleaning up after them. Despite telling them about my condition before moving there, which they said they understood and agreed to accommodations needed, they don't. (I have POTS by the way, I only just remembered to maybe mention that) this condition is exacerbated by heat. 
During the summers here it gets to the 100s sometimes, and they leave the AC at 78 degrees. All summer. I overheat and continuously pass out. I've been hospitalized 5 times for over heating and even the doctors have told them to utilize the AC. They still don't lower it. & their reason for keeping it high is because if it's any cooler it messes with their sinuses. 
They also leave messes constantly in the kitchen for us to clean up. But the one time I left a plate in the sink, I got complained about to my boyfriend. & anytime they have a problem with me, they just tell my boyfriend. I would much rather them come to me to discuss any problems that are concerning them. 
Another thing that's adding to all the stress is his mom is VERY excited for this baby. It will be the first on both sides of the family. But she's coming off very strong. She keeps calling my baby, 'her baby', and that she will 'sometimes' let me hold her. & she just keeps making these comments that are starting to bother me. I know they're from a good place, and I love how excited she is, but good lord. It's MY baby. & she's not even born yet, so please back off!
Also, we just found out that my boyfriends sister may be moving in with all of us because her and her boyfriend may break up. This adds a whole new level of stress for me. She is extremely overbearing, opinionated, wants to be up my boyfriends ass 24/7, makes side remarks over everything I say or do, one ups everything, and she alwaaaaaaaays has to be right. 
I'm just so stressed out now! I've been officially bedridden by my OB, and all of this is just making it worse. I'm really concerned on how to establish myself here, and how to raise my daughter with my boyfriend, while living with his family. I want us to be able to have a sense of family with just the 3 of us. But I don't foresee his mother or sister allowing that. 
They're both very similar and I don't know how to act around them. I'm usually always quiet, and just go with the flow. But I'm worried that they'll try to overstep their boundaries and try to take over my daughter. 
They both make comments about taking my baby with them and letting her sleep with them, and doing all the feedings and wanting to be in the delivery room and just so much stuff! My own mom won't be there because she's in Ohio, so I'm not sure what makes them think I'd want either of them there in the room! 
Moving out isn't an option for us. We can't afford to live on our own right now, and my boyfriend really wants to just focus on finishing up college and then move out anyways. I just don't know how to cope with all this, or how to stand my ground better. I'm a VERY timid person and just very shy in general.