Welcome to HCM forum
If the urine test is negative then there are less chances of pregnancy
But to be more sure it is better to get an ultrasound
to exclude any ectopic pregnancy as you are having severe pain
Repeat the test after 15 days if you don't get periods.
There can be PCOD which is the most common cause of delayed periods.
Get your thyroid profile done as hypothyroidism
is usually associated with delayed periods.