Hello..
Apart from pregnancy there are many causes of delayed periods like stress, anxiety,
thyroid dysfunction, increased
Prolactin level, obesity, certain medications & most of PCOS..
Though tubectomy failure is rare but still do a urine for
pregnancy test..
If pregnancy test is negative than you may require the following investigations:
USG LOWER ABDOMEN
BLOOD FOR CBC,
sugar,
TSH & PRL ..