Try putting both hands on top on your head. That's what they always had us do in gym class when we were out of breath lol. It expands your ribcage so you have more room for bringing oxygen into your lungs.
I'm 24weeks and 5 days.. I thought I was alone. I have to say being short of breath is somewhat frustrating.
I have that also, I have a desk job my doc said it's from sitting to long. So I make sure I don't sit longer that an hour at a time. Stand and walk for a few minutes it seems to help.
I'm due the 31 it happens to me as well I try to recline if possible and put my feet up it helps a ton. Also wearing loose clothes as mentioned especially pants
Yea I'm due August 30th and notice when I'm sitting down sometimes I'm short of breath. I think out lungs are getting pushed up by our growing bump...I try to wear loose clothing it seems to help a tiny bit