There are actually several signs of pregnancy.
Your doctor may tell you of all the possible signs including the major symptoms.
This article may hint you that you are pregnant as it provides three early signs of pregnancy:

1. Menstrual Delay - Menstrual delay is always the first hint that you are pregnant.
   Some women may have irregular menstrual cycle and may think that she just missed her menstrual period for the month.
   She might take it for granted.
   When you are sexually active, you should always take menstrual lapses into consideration.
   If you just had sexual intercourse previously, then getting pregnant may be the next big thing.
   Some women may also have regular menstrual cycle.
   This will not be a hard to determine whether you are pregnant or not.
   
2. Morning sickness - Morning sickness can occur several days after missing your period.
   This can be in a form of nausea and vomiting.
   Pregnant women can feel nauseated all the time.
   It does not usually occur in the morning.
   It can occur anytime of the day.
   This is a stressful time for many pregnant women.
   It may be very difficult to adjust and get used to it.
   This is one of the earliest signs of pregnancy.
   
3. Urinary frequency - Urinary frequency is also one of the earliest signs of pregnancy.
   This is due to some hormonal changes a pregnant woman may experience.
   It may also be due to the compression of the urinary bladder with the growing fetus inside the mother's womb.
   

These three signs are just some of the earliest signs of pregnancy.
If you want to make sure, you can always do the instant pregnancy test or you can consult your doctor regarding this.
Your doctor is in the great position to reveal everything regarding your possible pregnancy.