I had an unprotected sex with my girlfriend,I gave her emergency contraceptive after sex that also within 12 hours, and she got periods on the 7th day after sex, period was there for about 2 days. Will she be pregnant?

IF she had her period then chances are no. A woman's Period is a pretty good determination for not being pregnant. Two days is a shorter then average period, but that is also probably because of the Emergency Contraceptive that she used. The Emergency Contraception is a LARGE Burst of hormones that will prevent pregnancy. The side effect is that it will usually cause a number of irregular cycles.

During this time I would suggest that you find an alternate form of birth control. The Emergency Contraceptive Pill is great for "Oops" moments, but shouldn't be relied upon as your main form of birth control. Condoms in conjunction with a hormonal birthcontrol is usually effective. I would also suggest that you talk with your girlfriend about what you two would do if she got pregnant. No birth control is 100% effective.

Possible, but not likely. Any birth control, even emergency contraceptives, are not 100% effective, so some women will still become pregnant even with proper use. Given that, the effectiveness of emergency contraception is quite good. However, if having sex is something that the two of you will continue to engage in, using a form of birth control on a regular basis is more effective. That would include things such as the pill, injection, implant, etc. and you using a condom. Emergency contraceptives should be kept just for emergencies... not for regular, routine use, just so that you are aware.

The bleeding that she had may have been bleeding caused by the emergency contraceptive, a common side effect, so she would need to wait and see what happens when her period would be expected next.