Delay in Period - UPT test negative.

This is 3rd month of ovulation induction. For first 2 months I had taken Leterozole 2.5 and then followed by follicular study. I was ovulating on day 12. This months I have taken same medication, only have not gone for follicular study. But as per symptoms it seems I have ovulated on day 12. Then on day 28 (16 days post Ovulation), I did urine pregnancy test & it has come as negative. Today is day 30. Till now no symptoms of period. I had very light spotting on day 19 & day 21 (total 2 times brown and pink colour 2-3 drops of spotting). I am very confused now. As urine test came negative on 16 days post ovulation, so can I still be pregnant? Or what might be the reason of delay period? I have always regular 25-26 days cycle. When to go & meet with doctors. Currently I am stuck in my father health issue, so came here to the suggestion online. Please help in this. My kind request to all. Thanks in advance.