Last month my period was almost a week late but then started for 2 days and now September 4th I am having pain in my lower abdomin and I'm not due for a period till around the 20th

If you have sex, you can get pregnant.
The pain you have could be too many things to list here. So see a doctor.
Your period being a bit late is meaningless. Not sure what you mean by 'started for 2 days.' If you mean, it only lasted for 2 days, that's meaningless too.
Yes, it's possible to have a light period the first month of pregnancy, but again, it proves nothing.