Thanks for your query at DoctorSpring.
Apart from pregnancy, there could be various reasons for a skipped / delayed period .
Firstly, a delay of a few days is normal in some women - it is nothing to worry about, as long as the majority of your cycles are regular, and this is a one off occurrence.
Secondly, any form of stress and anxiety could affect your periods.
This could be emotional stress, hectic travelling, frequent late nights or long hours at work, recent and rapid changes in your weight.
Some concurrent medications ( for eg. - antipsychotics ) also affect the menstrual cycles.
Hormonal imbalances , particularly altered levels of the thyroid hormone or prolactin hormone can cause delayed cycles.
Some disorders of the uterus and ovaries, namely - polycystic ovaries and endometrial hyperplasia ( thickening of the lining of the uterus ) can cause menstrual delay.
You have not mentioned your age, in the extremes of reproductive age, such as around menarchae and around menopause, such changes are common. Does not apply in your case, but after childbirth or an abortion also, such a picture arises.
Infections that damage the endometrium can cause menstrual delay.
As is obvious, apart from pregnancy, there are countless causes of a skipped period.
You would have to provide more details, if any of these reasons sounds relevant to you, for me to give you a provisional diagnosis.
A basic Gynaecological check up ( per vaginal and per speculum ), alongwith pelvic ultrasound, and hormonal level measurements, would help in letting you know the specific reason for the delayed period.
I hope this was helpful to you. Please feel free to ask any follow up questions, as I would be happy to answer them.