I feel sorry for you because I think that you have been trying hard to deal with difficult circumstances for years. You got away from your husband and what he said and did in the past. You have a younger teenager with problems and your waiting to see if she has autism.
Your 17 year old has now come pregnant, smokes weed and is on my medication. Her boyfriend is from a bad family, has no job and smokes weed also.
Your daughter wants to keep this baby and probably thinks she and him will get a house and benefits. She probably thinks as well that if she has a baby it will keep him with her as well.
I tell her that she won't get a house or flat from the council if she has this baby and she can't stay living with you. I also tell her that you can't afford to give up work and bring up this child. Tell her as well that her 17 year old boyfriend does not want a baby and he will be out cheating on her once he gets the chance. Tell her that he get sick of her and a crying baby and he will leave her on her own with a baby and no money. Ask her how much are nappies and a tin of baby milk? Tell her she have no money for weed, night out ect and meanwhile her friends will be going to college, university, getting job's, travelling and perhaps living abroad in the next few years and she be stuck in a horrible flat with a baby, no boyfriend and no money.
I tell her that she be better off having an abortion and getting away from that boyfriend. If she does this you will help her get back into education so she can have a better future.
If she refuses to listen to you and would ring the police and tell them her boyfriend is dealing weed and get him arrested in front of her. From what you said his whole family are fond of weed and a police search in that house should find weed.
Perhaps getting the boyfriend arrested might make her see what life will be like with him.
I tell her as well that if she has the baby she will have blood and urine tests in hospital and that the internal tests they do are very sore also. That social services will be involved and will call to see where she is living and seeing her smoking weed.
Then social services will take the baby off her and by then her boyfriend will have another girlfriend.
In reality what 17 year old lad wants a baby? His parents might think it fine having a baby at 17 but a baby is hard work. Even a strong relationship with parents who planned a baby in their late 20's/early 30's can find it hard going.
One of my friends had IVF in her 30's and she said that being pregnant and the 1st 6 months after having the baby were far harder both physically and mentally than she expected. She had a house, money and her husband was very supportive also.
I know several girls and boys aged 17 to 23 and they are all in university, working part time during college and full time during the summer. They are saving hard to go away for the odd weekend or to have a cheap foreign with friends before going back to college. None of them want kids for a long time yet.
If she continues with this pregnancy I would be contacting social services and telling them the full story of her, him, his family circumstances etc. I would also tell the hospital about her as well.