I am a massage therapist and have often seen wrist pain/hand numbness connected to the muscles in the neck and shoulder. Your nerves and arteries pass through your tiny neck muscles (scalenes) which are in the triangle between your collar bone, neck and shoulder.
If you have a lot of neck tension (from breastfeeding, carrying baby, etc.) then these little muscles try to help and become inflamed. This causes an impingement on the nerves going to your arm and hands, resulting in numbness, pain. When this condition gets severe it is called thoracic outlet syndrome.
Just think about how often you have your head leaning forward -that is 10-14lbs that your small neck muscles have to support for extended periods. No wonder they get exhausted (as do we!!!)
Try massaging the area above your collar bone with you OPPOSITE hand while sitting with your head resting on a support (like a high chair.) Go ahead and apply a lot of pressure and see where it hurts. You wont break anything in there, but if you feel any of the pain radiating towards your arm, then this may be your problem.
The good news is that massaging the area stimulates circulation which will help reduce the inflammation and thereby reducing your symptoms. Give it a try, or go and get a quick chair massage at Whole Foods. Just tell them where you would like them to concentrate on.
I hope this helps!