Shortness of breath

In 29 wks pregnant with twins and i know they said shortness of breath is normal by now. But it's quite bad for me that even when im standing for a few minutes, i have to catch my breath. Sitting comfortable is a struggle too. Working in the early childhood industry isnt easy either. I went to KKH and they gave me 5 days mc to rest but its coming to an end and i still feel the same. Any tips of managing? I've done stretching, breathing exercises but still the same.