30 weeks and working

I am 30 weeks and I work as a dental assistant in a busy office. On my feet and walking down the halls pretty much all day for 10 hours. I am absolutely miserable and tired. I am only 5'. And have diabetes and a lot of patients comment about how huge I am.. it's hard to even walk because the baby feels sooo low. When I come home my feet are swollen and my whole body hurts. I feel like all this working is going to make me go into labor early.. any thoughts?? Anyone else struggling through work with me??