Hello,
Chances of pregnancy just two days before periods is less. Apart from pregnancy, there are many other reasons for a delayed period. The other causes are hormonal imbalance like in PCOS (Polycystic ovarian syndrome), stress, obesity, malnutrition, anemia, hypothyroidism, illness, etc. The only way to know whether you are pregnant is to get a pregnancy test done. You can do a home pregnancy test by using a pregnancy kit easily available at chemists. Also, it is suggested that you see a gynecologist who will examine you.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
There are a lot of things that can change your cycle, emotional and physical stress can do the trick. There are specific times of the month that a women is ovulating and more likely to get pregnant & you can still get pregnant while on your period. A condom is very effective as long as it is used properly and donesnt have a hole. Birthcontrol is also effectve, but women...yet again...can still get pregnant on birthcontrol. When I stoped taking birthcontrol 6 months ago, after taking it for 5 years straight, I didnt have a period for 6 months because my body was adjusting.