Hi,
Can you please clarify what "breast kyphosis" is please? I am guessing that you have thoracic kyphosis.
Chiropractic - and i am guessing because i don't know your chiro personally - usually just uses adjustments to alter the spinal joints (and rib joints in your case perhaps) in an attempt to "normalize" spinal nerve function.
From a physio's point of view, that is fine but it may be that the adjustment causes a reflex relaxation of the spinal muscles which is the temporary relief of pain.
I personally use "adjustments" in my clinical practice but they are ALWAYS teamed with stability exercises which will eventually reduce the need to have future adjustments - otherwise you end up needing adjustments for life!
Find a physical therapist or osteopath whoc is well trained in the treatment of the thorax. The world's experts in thorax treatment, management and rehabilitation (IMHO) are Diane Lee and LJ Lee. ASk if your therapist has been trained by them in the thorax. Otherwise Muscle Energy Techinques for the ribs might be a sufficient substitute (but not as good because of the rehab component).
Good luck! BTW, more details usually gets better responses!