Slow down. As if there weren't enough hints in this thread already.
There are several recent threads that include various philosophies on breathing. Basically it comes down to "do what works for you". I can't get enough air just through my nose and breathe mostly through my mouth. I typically breathe in 3 out 2 or in 2 out 2. "Belly breathing" yes, using the diaphragm helps to do a better job of filling the lungs.
But going a little slower will do more at this point tham playing aroung with your breathing.