I feel like when i breathe in I'm not getting enough air in?

I keep taking deep breaths and i feel the air going in but then /i don't feel it/ as in it's not enough. i keep taking in deep breaths and the only time i'm getting in enough air in is when i yawn, and only like 2/5 times it's enough. When is stand up I get dizzy, and i've noticed this whole process happening quite often now. My hands keep shaking but that's nothing new, i've been diagnosed with anxiety disorder and my hands have a permanent shake in them. I don't know what's going on, help?

Also, as soon as I'm a bit better, and it's easier to breathe, I become extremely exhausted.