if your UPT is negative you might not be pregnant , the market availabe UPT instrument are pretty sensitive so they can pick up quickly if you are pregnant or not, stress
is another condition which delays period, so relax and am sure you will have your menses start again , nothing to be worried of. Yellow dischange might be coz of infection For example, there will be more discharge if you are ovulating, breastfeeding
, or are sexually aroused. The smell may be different if you are pregnant or you haven't been diligent about your personal hygiene.