Hi thanks for your question.
You had your last period on 28th of march after which bled for 19 days, which means you have to calculate you next due cycle after last day of this bleeding and not from the 27th of feb. You had unprotected sex after the last bleed and now you arer having symptoms suggestive of pregnancy
,like mood swing
and weight gain. All these are also side effects of Nothisterone. Your pregnancy test is negative. Now you have to differentiate between the side effects of nothisterone and pregnancy. Pregnancy test turns out positive 7 to 10 days after the missed cycle. May be you have got done your pregnancy test little earlier. Repeat the pregnancy test 40 days after your last cycle. If it turns out to be positive, it confirms the pregnancy, otherwise these symptoms are due to side effects of nothisterone.
Hope this answers your question.