Hi doc,
Last time I asked about my missed period, well I did a pregnancy test two weeks after I missed my period, it was negative.
Why is this, can it be something else that is preventing me from getting my period? Or must I go for blood test?

It means you probibly aren't pregnant... there are a number of things that can delay your period.. sometimes significantly... some women may even miss a period from time to time.

If you have such doubts and worries... book an appointment with your gynecologist.