Same here. I've felt that way for quite some time now. I don't think the shortness of breath happened until closer to the end with my other 2. But everything seems to be "more" and sooner with this one. LOL!
I have been having it since about 20 weeks. I have found that putting my arms on top of my head, or slinging them over the back of the couch, or on the "wings" of a wing-backed chair all are positions that help me to breathe better by lengthening my torso and ribcage a bit better.