My LPR mom doesn't have a childhood photos with me and my birth certificate was late registered hope a DNa can cover all those missing documents?

Have you been asked to produce anything beyond the birth certificate at this time? If not, you are stressing over something that may never become an issue. If so, a DNA test can be conclusive evidence of the mother-child relationship. The DNA testing must be conducted by an authorized organization. You can read more about family immigration at http://myattorneyusa.com/family-immigration.