First of all, I suggest to undergo one blood test
for beta-hCG (more reliable) to confirm pregnancy
Other reasons of late period could be ovarian cyst
, hormonal imbalance, over wt, mental stress, emotional upset, eating disorder
On negative blood test, one USG lower abdomen and hormone test will be worthwhile. You may require hormonal pill to induce and regularize 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.