Hello, As you got your period on 20th June (following intercourse) and recent pregnancy test is NEGATIVE, then possibility of pregnancy has been ruled out. Other reasons of late period could be PCOD, hormonal imbalance, over wt/ extreme loss, mental stress (most common), emotional upset, eating disorder, thyroid problem etc. Here, I suggest to await for another 1 week for natural period and if you don t get it by this time, you must undergo one USG lower abdomen and hormone test to confirm the diagnosis. Kindly, consult with your gynecologist and take advice accordingly. You may need to take progesterone pill to induce period. You should control body wt, avoid stress, take healthy low carbohydrate diet with avoidance of fatty food and sleep properly. Be well and good luck.