When To Take Pregnancy Test. The test. ?

Hi ... I have been taking medications for conceiving. Jan 15th was my last period date and I went to doc on Jan 19th ,,, she suggested for Folicular study from Jan25th, also suggested me with Letroz tablet from taken from 19th Jan to 23rd Jan.. On Jan 25th my egg was fully grown and got injection for egg rupture.. On Jan 27th Egg got ruptured as on Folicular study reports.. Doctor advised me to take Drolute 10mg tablet for 15days from Jan 27th  (1-1-1). Along with folic acid.(0-0-1) On Feb 3rd I saw a small drop of blood in my Inner Thinking that shud be my spotting or Implantation bleeding or something. .. Today 10th Feb is my 15th day but pregnancy test is Negative... also I didn't find any pregnancy symptoms as of now but small cramps occur daily. Plzz suggest and Guide Is Im Pregnant or Not and When should I repeat the test.?