I had sex the day after my period, we used condom and as I said we checked it after that, every thing was OK. But I have'nt gotten period yet. I used pregnancy check also twice and it was negative but I'm still sooo worried. Can anyone help?

Any time you have sex, pregnancy is possible. No form of birth control is 100% effective, and condoms have one of the highest failure rates of all birth control.

How late is your period? When you tested did you use first morning urine? It may be that it's too early to test.

Wait another week or two and test again if you still haven't gotten your period. Use first morning urine. If that test is negative than wait until your next period is due and test again if you don't get your period, or see a doctor for a blood test.