I've felt like this most of the day. I can breathe in and out just fine, I'm not short of breathe, but for some reason I feel like I'm not getting enough oxygen. And it doesn't matter if I'm sitting, standing, or moving around. I know towards the end of the pregnancy it's common to be short of breathe (again, which I'm not), but is this common at around 14 weeks?
Oh, and it's not like OMG I CAN'T BREATHE....it's just a minor annoyance.
Re: I feel like I'm not getting enough oxygen.
Married since 06/19/2004|Anna born 11/19/2006|Charles born 11/1/11
Double undergrad graduation May 2011| Me: Psychology, DH: Communication| A long journey!
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It's definitely not from my bra. I've not been wearing one most of the day so far.
Don't worry though, I haven't left my house braless! 
I wish I had an oxygen tank and little mask thingy! I don't know if that would necessarily make this strange feeling go away, but that's what I'm "craving" right now!
I know the feeling!!! I had it off & on before pregnancy. I just figured that it was from my struggles with iron deficiency. I have it more often while pregnant & I have to take much deeper breaths (more like gasps for air) sometimes.
I've been having this same problem since I started showing. I think everything is all squished in there. So it makes it a little harder to breathe.
That's my theory anyway. It's very annoying.