What is the longest time it can take for hcg to show up on home pregnancy urine tests? I think I am about 6 weeks pregnant according to opks predicting ovulation time, plus nauseous and headaches. However all preg tests are negative. No period yet but have pcos so not too fussed about that. I am overweight. I read that that can affect hcg levels. Just wondering if it is possible to be pregnant and not have hcg show up. What is the longest anyone has had before it showed up?