Stay at home moms with toddlers

How are you coping with your pregnancy with a toddler running around?  I am 24 weeks and my daughter just turned 3.  I also watch a 2 and a half year old full time during the day.  I would love to tell the parents of the 2 and a half year old that I can't watch him through the rest of my pregnancy because it's getting to be too much for me but we really need the money.  My daughter has not been sleeping through the night and when she is sleeping I am tossing and turning.  Neither of the kiddos nap during the day and my husband has been working late almost every night which will be going on for atleast the next month.  I am struggling to cope, I am beyond tired and so need a break.  Just curious if any of you other pregnant mommies have some words of encouragement or advice.  Thanks from one exhausted mommy!