Warning DRAMA and long rant

TL;DR 19 yr old sis inlaws pregnant super not ready.

So we just found out my sister in law is pregnant and I am extremely worried for the baby. First of all she lives with us in a house that originally belongs to my father in law, however he has another property on which he lives with his wife and other son. The last two years have been crazy for her she dropped out of high school got into pot cigarette she used to leave for dysfunction at a time with our telling anyone where'd she'd gone, she had come home drunk a few times and has gotten into several disagreements with her parents. My DH has always been close and supportive of her but after multiple times of trying to get her to clean up her act he got tired of it and just stopped talking all together with her even though they live in the same house. Since I knew she's been suicidal and had depression I tried to be nice to her and give her advice and make sure she has someone to talk to. Anyway fast forward a 1 months into us fully moving into my in laws old house she started having her boyfriend over over night several times even though she knew that that was not ok with us because we have a young child and don't know or trust him. My DH and Mother in law and her have a disagreement and I end up the bad guy because I'm the one that noticed she was having him over (I'm not stay at home mom), we'll this did absolutely nothing bused get her mad at me because her boyfriend is here almost every single day. I also end up having to tell her that our son is not allowed in her room because it's, we'll disgusting (though I don't use that word). She gets visibly upset with me and left for the weekend and didn't come out of her room when she came back. she never cleans anything in there never vacume her carpet which is stained with by so my things and soda spills, her mattress in also stained old and looks like it belongs in the street her widows and just covered in dust, it's so bad that every time she opens the door I can smell the stench all the way across the house. Her solution to this is to burn candles to lessen the smell. In the year since we moved to town she hasn't cleaned her room once. She rarely cleans her dishes unless she feels like it or if she uses a big pan, and never cleans the kitchen when she makes a mess even on the stove. She also blasts music in her room every single day.

About a couple of month ago she started vomiting a lot I told her mom because in our town there's a really nasty stomach bug going around, and around this time she also started getting better with my DH whom tells me she's always vomiting anyway and brushes it off. About a week ago she finally tells us she's pregnant and does the know exactly how far along she us just that it's been about 4 months. She's known all along and hasn't done a thing to take care of herself. She drinks 2 cups of coffee daily and is not atopic g by the looks of it and it's very little mostly junk food and still locks herself in that disgusting room. Ever since she told us I've given her books and my son's old baby clothes, I've offered her advice and I told her she can have anything that she needs that we have from when our son was a baby. I've really tried to be helpful I've even begun to invite her to have healthy meals with us and even took her to buy prenatal vitamins. But I am still incredibly worried for her baby and her. She has no plan, no car, no job, and although she does seem like she loves her baby she just doesnt seem willing to take care of herself. I know it's not my business but I seem to be the only one that cares. Her mom is always more worried about having her like her that she's stopped being her mom and instead seems like she's trying to buy her affect on. I really just plan to back off at this point.

Sorry for long rant. any advice?