In the sun salutations you breathe deeper than ever, this is why each move has one breath. Yes, the breathing has to flow rhythmically but when you do it deeper you can expand deeper, not only in your physical body but also in your mind.
It is like when you are swimming, you have awareness of that space between inhalation and exhalation.
I'd like to confess to you that I asked that question to my teacher long time ago. I was a little frustrated because I could not follow his breathing pattern during the sun salutations. It felt so long for me. Ugggg!!! He replied that I need to learn how to breathe deeper. One movement is one deep breathe. So I am totally with you in this one. One day after fainting I understood! I do not want you to faint! So you do not need to force anything. You will learnt to breathe deeper during the sun salutations. Come to class, practice makes masters!