First of all, you should undergo one blood test
for beta-hCG (more reliable) to confirm late conception.
Other reasons of late period could be hormonal
imbalance, over wt, mental stress, emotional upset, eating disorder
If you don't get your period within 1 wk, then one USG lower abdomen and hormone test will be worthwhile. You may require progesterone
pill to induce period. Kindly, consult with your gynecologist and take advice accordingly.
Control body wt, avoid stress, take healthy diet with avoidance of fatty food and sleep properly.