I Am 20 Years Old. I Had Sex With My

I am 20 years old. I had sex with my partner four times in around 2 months. Each time our precautions failed. I took unwanted 72 birth control pill after each intercourse within 12 hrs. Now I am not having my periods regular. There are periods but they are just the side effects of the pills which stay around 2-3 days only. I have headache, leg pain, tiredness and stomach pain. Am I pregnant? Are there any longtime and serious effects of taking this amount of pills in 2 months?