SO uncomfortable

So I have a desk job... I'm 27 weeks (tomorrow) and I am so uncomfortable. If I'm sitting I get so out of breath and random spells of light headedness. My torso is super short and he's growing so there's not much room for him to go... I've heard this issue could be cause from the vena cava being cut off from the weight of your uterus.. so my solution was to try standing. Well it makes it harder to type while standing and then my back starts to hurt. Anyone have any remedies?! I am willing to try anything cause I just can't concentrate on work. My boss has been very understanding and flexible with me through this whole thing, but I just don't want to keep asking for exceptions.