Mother in law?? Do’s and don’ts??

where can I start off in the nicest way possible?? Sometimes I don’t get it... I truly dislike speaking on behalf’s of others because everyday someone is fighting their own battles or dealing with their own problems we know absolutely nothing about. Now.. here we are addressing the issue on an anonymous website because we have no where else we can share our thoughts or voice our opinions!! I can’t seem to understand in laws, why do they always think and speak like they are above us?? I am currently 38 weeks pregnant this is my second child, with a second father my first child’s father is and has never been in the photo. I have raised my son by myself with the help of others for almost 6 years now he has always lived with me and I can’t say I’m the greatest mom but my son has always had everything he needed/wants. I am in a relationship with someone who I truly care about and would like to spend the rest of my life with. We both live together in a different city we are approximately 50-1 hour away from his mothers house. Every so often we come to visit, btw when we come her house is never clean she has a dog who lives inside and is allowed to urinate and poop anywhere around the house including my SO’s old room they don’t make it a priority to clean it up there’s been one too many times I’ve stepped in it because it’s everywhere. sometimes when we go over I don’t bring my son because she has three kids one 21 one (25 my SO) and one 8. The 8 year old doesn’t have much manners and is very rude/anal when it comes to his things, he doesn’t like sharing and he also dislikes being told what to do. My first child who’s 5 picks up very bad manners and behavior from him. There has been times where I have to discipline my child because I am his mother and I’m trying my hardest and best not to raise someone disrespectful. I enforce rules, my mother in law doesn’t agree and says I shouldn’t discipline him because she doesn’t discipline her 8 year old. I cannot tell her how to parent her child because whatever works for her may not work for others. to avoid the problems or argue meant I just avoid bringing him. My second child is scheduled to be born December unsure what month it may fall on but my original due date is December 28. I am not big, I have only gained 21 pounds in this second pregnancy I try my best to eat as much but I still have really had morning sickness (all day sickness) I throw up a whole lot, I’ve had severe pain such as mild cramps I can feel within my but, hips and lower stomach, I’m carrying high but I just had my 37 week ultrasound and baby has completely turned and is in a head down position. So my mother in law continues to tell me it’s too soon to give birth this month and that she believes the baby will be born around January, that I have not dropped and that the baby is still super high. (clearly she isn’t a doctor).. then the baby names are still in question for me and my SO (significant other) we haven’t decided but we did share our ideas to both our parents not for validation but just to give them an idea of what we have in mind. My mother in law doesn’t/hasn’t agree with any names I have mentioned so far. Every name apparently has something wrong with it. Making it difficult to agree on anything with my SO because she is putting things into his head. She states that she wants our child to have a Hispanic name so that she can speak to my child in Spanish. My child’s name shouldn’t be based off of someone else’s opinion. She recently came to my baby shower and got very waisted, she knows how to carry herself well while drinking plus she’s an adult, that wasn’t my problem my problem was she and her husband who was also drinking started speaking on behalf of me to my mother and step father she was speaking very poorly of me in Spanish making it hard for me to understand I am Mexican but don’t speak fluently my Spanish is very poor and could use some work. Today I’m 38 weeks and we came to sleep over and visit for a night less than 24 hours as we leave in the morning to avoid problems we let her know in advance we were coming over, we come into the room with toys and a huge mess all over the floor, making it hard to even get to the bed and having to pick up ... I about had it with her I feel like more or so there was a mess purposely placed there.. we let her know in advance we were coming over surprisingly her house expect this room is spotless and looks beautiful with Christmas decor etc.. I may be pregnant and it may just be my hormones but I just need some guidance some reassurance some hope some advice that I’m not alone I’m going to give birth soon and of course that’ll be her grand child but I’m just worried I don’t want anyone in the birth room besides my so because I’m not comfortable with my body being exposed.. I’m giving birth where I resign not in her area which she always brings up my insurance doesn’t cover that location making it a challenge for them to drive 50 minuets away the baby is coming home with me. I don’t plan on having a new born back and fourth from city to city... I don’t know what to do. My SO thinks I’m being selfish I’m being realistic... I’m exposing the truth for what it really is god my relationship is also falling completely apart because of this .... idk what to do. Ladies please help down below