Am I Experiencing Withdrawal Bleeding Or My Periods After Taking I-pill ?

i had sex on 15th june and took ipill after an hour ..i had some minor stomach cramps and tender breasts after that..normally when i have my periods stomach cramps happens and from today morning iam having stomach craps and bleeding i think its my periods but m bit confused weather thats withdrawal bleeding or periods ..i think its periods ..what do u think doctor ..m a bit scared