Whether or not you establish you have Diastasis Recti, make sure your doctor checks for an abdominal hernia. Larger hernias can prevent the diastasis (separation) from healing, plus prevent you from exercising. And some hernias require surgery since it’s a protrusion through the cavity wall. Otherwise you should be able to create a healthy core again, even if you have the diastasis or a small hernia. Although, you should not exercise if your hernia causes pain!
Please see Diastasis Recti Test for how to self-evaluate if you have diastasis recti.