Lazy & sleepy during third trimester

Hi, I’m a promoter working at electrical store selling refrigerator & washer. I was pull into this line by my husband as soon as he realise I was pregnant, as his company allow me to get maternity leave. But recently things have changed ever since I enter my third trimester, I became really sleepy & tired, I don’t have the energy to run around the sales floor catching customer (Our job required a lot of standing, running & talking to customer) & now even to the extent I’ve been taking mc & leave whenever I’m lazy to go to work. My husband is furious about my Performance at work and ask me to reflect myself as I’ve been losing to my competitors brand. I tried to explain to him that I’ve never experienced this tired in my life and he said it’s just an excuse because every pregnant lady he know isn’t as lazy as me. I find myself having the right to rest but I felt bad for letting my husband and company down. Will I still be this tired after my baby is born because from what I know it is even worst. I’m thinking of quitting after my maternity leave since I’ve bad performance nowadays.