What is the best way to get diagnosed with diastasis recti?

I am sorry to hear that you have been having such a difficult time.  Diastasis recti (separation of the "six-pack" rectus abdominis muscles) is a common problem for many women, particularly after pregnancy.  Patients often experience a bulge between the separated muscles.  The diagnosis is typically made by a physician through physical examination.  The condition is treated by suturing the muscles back together again in the midline.  This is most commonly performed along with a tummy tuck in which loose skin is also removed to give the patient a flat, attractive abdomen.  I hope this helps.
Ziyad Hammoudeh, MD

Though it is true that many if not post patients with diastasis recti have no associated symptoms, there are certainly others who do. 
Symptoms that may be associated with diastasis recti include back pain, bloating, tearing/ripping sensation, feeling pain of intestines within the diastasis and worse with meals, and constipation. 
Urinary incontinence is not a cause of diastasis recti. However, a) it may be an indication of overall muscular/collagen disease after pregnancy and b) it may get worse if the diastasis recti is corrected.