The risk of pregnancy is generally low. However, variations in cycles, stress, and other factors can cause period delays. Consider emergency contraception if needed, and if your period is significantly late, take a pregnancy test.

If you missed your period and are worried about being pregnant, the best thing to do is to take a home pregnancy test to confirm whether or not you are pregnant. These tests can give you a reliable answer within a few minutes. Even stress or some other hormonal or health issue can cause a delay in your period. Kindly check with a gynec.

At 12 weeks, the 2 cm head size of the baby displayed in the scans is normal. This is nothing but a predictable growth pattern. The baby's brain will continue to grow to the same body proportions during the pregnancy. An infant's cranial size at this stage is crucial in the development of the brain, thus this is an important parameter to control. 

From the beta hcg values, it appears that you are not currently pregnant. Irregular periods are often symptoms of other medical conditions. You should consult a gynecologist in order to review and diagnose. They can recommend you proper medical advice and treatment regarding your condition.

If you are observing a shorter than usual menstrual period, it could be that the cause is stress, hormone imbalance or a certain drug. It is advisable to visit a physician who specializes in women's reproductive health in order to diagnose the problem and to receive proper treatment.
 

It is perfectly natural for blood flow to be inconsistent during a menstrual cycle. Sometimes it may be lighter with less cramping. It’s quite common to experience a fever and body aches while menstruating – this doesn’t necessarily mean that you are pregnant. However, if you want to make sure, take a pregnancy test after your period ends. If your symptoms are worrying you, keep yourself hydrated and get plenty of rest.