Its highly unlikely you are pregnant if you are having period-like bleeding - this can happen, but it is very rare.
That said, if you have reason to suspect you are pregnant, the best thing to do is to take a test.
As a side note, the withdrawal method is not a form of birth control.
Pregnancy and period symptoms are so close that it is usually very hard to tell if you are or are not. I don't advise anyone to use to pull out method seeing how I'm 15 wks preg from using it. If this is a monthly thing that has you on edge and your not trying to have a baby why not use some form of birth control to make sure theres no unwanted pregnancy. A women can bleed while pregnant but its usually not like a normal cycle. The color is either off or the time span. All the symptoms you've listed just seem like your body is changing and your period is changing as a result of it. Its very normal for all these things to happen with your period. It will probably go back to how it was in a couple months. All the joys of being a women right ;))