Need work advice ladies

This may be long so I apologize in advance. I have worked since I was 16. I’m now 24. I was 16 when I had my first and began working after, with my second (2 years ago), I worked up until 38 weeks although my doctor advised against it due to placental abruption, but I had to make money to support my older son and the new baby. Fast forward to now, and I am now with someone who makes a a few dollars more than me and I make more than double minimum wage. We are well off. I’m now 12 weeks pregnant and working is killing me. I never thought I’d be one to give in or give up, which I haven’t yet, but I’m almost at my breaking point. I have a hernia that is so painful I can’t breath deeply or even stand up straight while I’m at work. My shift is 5:15pm to whenever-am. It’s mandatory overtime, we work til we’re done. It’s an assembly line for a vehicle manufacturer. Last night, I worked 13 hours. I lift 40ish pounds 500 times a night, once a minute. We have a time to be done with our station and start on the next- 56 seconds to be exact. No air conditioning and it’s been 90’s or better where I live. We only get a 20-30 minute lunch, one hour later than normal, for the whole 13 hours or how ever long we’re there. We obviously can’t eat on the job so I stay hungry and feeling horrible because of that as well. It’s difficult with how fast we run to get drinks of water adequately. My man wants me to quit and him get a second job. I won’t do it. I’ve talked to my doctor about short term disability and he wouldnt do it, he said my work conditions won’t hurt the baby so he’d like to keep me at work as long as he can. So I’m at a loss. Every night is a nightmare. I get little to no sleep with the shift plus an 8 and 2 year old at home that wake up shortly after I get home. I’ve thought about finding another doctor but I don’t want to be seen as just not wanting to work. If that were the case I would have quit the first time my man begged me to. My HR dept says there is no ‘light duty’, it’s either all or nothing. So again, I’m at a loss. Any advice or insight would be appreciated. Thanks in advance.