I agree with you.
There is always a possibility of pregnancy like thatquietgirl mentions.
I would go to see your doctor for a blood test to check your hormone levels and to see whether you are anaemic.
Best wishes.
I'm 26 so I don't think the menopause has started just yet!
I had an abnormal period about that quality (just spotting and delayed more than usual) before after having been on Microgestin about a couple years. It happens sometimes. If you want to be 100% certain, you could take a pregnancy test, but you should be fine.
You do not say how old you are.
It may be that your hormone levels have changed and you may be beginning the perimenopausal phase of your life.
If your period does not start normally, make an appointment with your doctor do a blood test to check your hormone levels and any iron deficiency.
Best wishes.