Why is my period flow slow and irregular?

If you have taken your Diane 35 pills correctly and consistently as prescribed then chances of becoming pregnant are very low. But if you have missed any pills or taken them late, the risk of pregnancy increases. Just to be sure you can take a pregnancy test. 

Pregnancy might be a possible. But you must visit a gyneclogist to confirm it, they can suggest you necessary tests to confirm pregnancy

I urge that any medication to terminate pregnancy should never be used without consulting a doctor. The misuse of the kit can cause discomfort and should be used only as prescribed. Missing periods after use of the kit could be a sign of some other problem. A gynecologist recommended for a full examination and clear advice on what to do next.
 

You didn't mention the pregnancy test and also even if it is possitive, you need to see your gynecologist. They can ask for some tests and confirm about pregnancy or any other health conditions
 

One of the most common side-effects caused by taking emergency contraceptive pills like Unwanted 72 is bleeding. It may change your menstrual cycle, either early or late period. But if the bleeding lasts longer or is more severe than normal, it might be necessary to see a gynecologist for an additional evaluation and therapy.