Can't breathe, please help.

I know shortness of breath is common during pregnancy, but I really do feel like my body isn't getting enough oxygen. To the point where I got very light headed at work today, and I often have to get up very quickly when laying down because if I don't I feel like I'm going to run out of air. I'm 29 weeks and I honestly feel like my body isn't cut out to be pregnant anymore. I feel like giving up.. 😔