Pregnancy question(s)?

I used to be a SAHM, then hubby's company closed(he put up cell phone towers/construction). So he took a job at the same place I am working. I am working 8.5-9 hrs day and a 40-45 hr. work wk. Hubby works full time too. We have other children at home. Youngest is 2yrs old. We literally work separate shifts so kids don't need a sitter. He gets home at 4 and I head out the door to work. Hubby wanted me to quit, but we do need the money. I am due in Sept. I'm only 24wks. I have had a few complications with my pregnancy. I sit at a desk(not allowed to put my feet up). Having lower back pain and my feet look like pillows they swell so bad. Dealing with carpal tunnel, I have wrist braces. Should I ask dr. to cut me back to 4.5 hr days vs. 8.5-9hrs. Would this really make a difference? Will my work allow it? Would dr. be willing to do this? Hubby thinks with the money we'd save in gas, headaches, etc.. It would be easier for me to stay at home. I don't. I think I should tough it out until at least 8 months.