I know this sounds like quite a stretch but I've heard of babies not wanting to latch when they sense that their mothers are tired or stressed out. Perhaps there is some truth to this and that's why your child is not latching on weekdays after work but instead on weekends when you are out and about, free temporarily from the worries of work.
To see if there is any truth to this, perhaps you can take a few days off work and see if baby latches as per normal? If she does, maybe there is indeed truth to the whole stress putting baby off latching theory. If this is the case, then you definitely should find a way to relax before nursing your child.