Physical limitations during 5th month of pregnancy?

I'm 5months pregnant, no complications, not a high risk pregnancy. As far as I can tell I'm healthy. And I work as a bagger at a grocery store. I was wondering if there are things I shouldn't do? My job duties include bagging groceries, picking up 50lb. Dog food bags, picking up 20pack soda boxs, picking up cases of beer other assorted lifting, pretty much any heavy lifting/carrying for customers or cashier. I also help customers out to the car and load their car for them.I also have to bring in carts from outside which requires pushing carts usually around 4or5carts at a time. Usually were assigned to bring in carts for 1hour 3or4times during our shifts, so I'm pushing carts a total of 3 to4hours per shift, &were not allowed to have more then 5carts out in the parking lot in any given time. So pushing carts is one of my concerns especially since where I live the heat has been into the 90s(degrees) recently. I just don't want to strain or hurt myself of the baby in any way. I would like to no any physical limitations that comes w/how far along I am. Thank you.