Can this lead to miscarriage? ?

First off im working two jobs. I've had my job at the tanning salon for a while, and all I do is run the front and clean the occasional tanning bed. But the shop is going to close soon, so I went ahead and got another job. The new job is a grocery store. They have me standing from 10-7ish with One fifteen min. Break and one lunch break. PLUS they rag me to go outside and get buggies! I'm 14 weeks, and by the time I get home I'm too tired to even eat dinner....