Call your OB. They are used to expectant mothers asking questions. I was probably the worst offender! :-)
Each pregnancy is different so it's not suprising you are experiencing different symptoms.
I am about 11 weeks pregnant and am already having difficulty breathing sometimes. I experienced that in my last pregnancy, too. It usually gets better if I sit down, relax, and take a few deep breaths. For some reason, I've noticed it more when I'm in the shower, but I'm not sure if there is a connection or not.
I also experienced the same "full" sensation you described in my first pregnancy. I had been looking forward to eating a lot, since I love food, but it was very difficult for me to eat anything throughout the whole pregnancy. I would be come so uncomfortable after eating even the smallest meals. I never experienced pain in my chest, but when I felt very full, I would get a LOT of pressure in my head.
Anyway, it never hurts to call your doctor or their nurse.
Congrats on the baby!