Even though your period is not very late (probably only a couple of days), I would still recommend going to see your primary care doctor
or your OB GYN doctor about this issue. In most cases, an early pregnancy (less than about 10 days) will not be picked up by the kind of urine pregnancy test that you can purchase in the pharmacy. Therefore, a negative urine pregnancy test doesn't completely rule out a pregnancy, and sometimes a more sensitive blood test (which your doctor can order) is necessary.
Also, there are many other causes of lower abdominal pain (with or without delayed period) that need to be investigated. These could be gynecological in nature, such as endometriosis
, polycystic ovarian syndrome, or a pelvic infection. They could also be gastrointestinal in nature, such as constipation. Finally, they could be caused by an infection in the urinary tract.
If you have severe abdominal pain, fever, bad nausea and vomiting
, severe back pain, or any other very concerning symptoms, you should seek help right away in an emergency room. If not, you should schedule an urgent care appointment with your primary care doctor as soon as you can to get to the bottom of this.