I'm 18 and I only took birth control pills for a month and one week. Right after I stopped taking the pills, I had my period right after on that Sunday. Its been four weeks already and I still haven't gotten my period. Could it just be irregular because my body is changing from not taking the pill anymore? My partner has not used protection but didn't ejaculate in me.

It is possilble that the hormones in your birth control pills knocked your cycle out of whack. You may just need time to allow your cycles to be regular again.

On another note, pregnancy is possbile for no form of birth control is 100% effective. It is even a higher possibility using the withdrawl method.

The only way to be sure is to take a pregnancy test or go to the doctor and get a blood test. Make sure you use your first morning urine, it is the most accurate.