so I heard you can't ovulation until hcg is under 5??

Is this true? I swear I'm having O pains but still have a faint faint line on a walmart cheapie. Someone said soon as my hits less than 5 you'll either get a period or Ovulate. I'm 2.5 weeks past my d&c. Bleeding stopped like a week ago. Spotting brown here n there tho. What's ur take on this?