Hi Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concern...
First of all you should check for
pregnancy, If you had done sexual intercourse since last month & in that case you might be pregnant now as you are late on your period. Pregnancy test done last month was negative meant you were not pregnant at that time.
If you didn't had sex since last month then you need not to worry. Sometimes delayed periods could be caused by reasons such as
hormonal disturbance, stress, ovarian problem etc.
White yellowish
vaginal discharge should not be sign of any problem if no
vaginal itching or irritation is present. It should be normal vaginal discharge. If your discharge is very foul smelling or there is vaginal itching along with this this could be sign of
vaginal infection.
Don't worry you should be fine
Refer to a gynaecologist if problem persists or reoccurs
Hope this information helps