Working while pregnant

Six months pregnant and really hoping some estranged, rich uncle we never knew about dies and leaves me his fortune. It's exhausting working 40 hours a week! I used to do it with no issue, and even overtime! Lately I just feel drained. Feet are tired, customers are EXTRA annoying (I work retail, 😣), and I feel guilty if I ask to take an extra break outside of my regular hour. Anyone else working til they pop (or until doctor says to stop) ?