Working while pregnant

Hey , at my job I do a lot of physical labor , I work in a warehouse , I move things and pick up things , I don’t feel a strain on my stomach while working here , my back hurts a little , but other than that nothing serious for me . I was wondering if it’s okay to do this , because I’m pretty strong , is it possible that I could be not seeing it as a big deal but it could be putting a strain on my baby without me noticing ? I was reading online that if you were doing a job before becoming pregnant your body is most likely used to it , but I don’t know for sure , my first baby ... Help ?