Hello,
If blood test is negative then it is highly unlikely that you are pregnant. 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. Seek a gynaecologist immediately who will take a careful medical history ,a physical examination, including a pelvic examination. . Blood tests may be ordered to examine the levels of ovarian, pituitary, and thyroid hormones. Imaging studies, such as ultrasound, X-ray, and CT or MRI scanning may also be recommended in certain individuals to help establish the cause of amenorrhea.
I hope it helps. 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.
It would be highly unlikely for you to be pregnant after a negative blood test and hpts. Many things can cause an off or missed period, such as stress, illness, hormonal changes, medication side effects, weight changes, diet changes or deficiencies, and so on. You can make a doctor's appointment to find out what is going on or just wait a while for your period to show up.