Cortef not working, Prednisone or Cortef?

Hi ya all. Just started Cortef / hydrocortisone yesterday. 20 MG per day. 10mg in am, 5mg at Noone and 5mg between 4-5pm. I'm not noticing anything and I don't know why because my dutch 24 urin cortisol test showed extremely low levels throughout the day. For instance normal range was 33-90 and I was .05. I feel soo tired. I'm wondering if it took some days for others to see results or if others have switched over to prednisone and saw a difference? Please let me know. I need my life back for my children's sake.