My girlfriend and i had sex and the condom didn't break, and we still took a plan b approximately 28 hours later. can she still be pregnant?

Yes but not likely: There is no such thing as "fool proof" with contraception. However, using a condom without breaking and using Plan B would make the likelihood pretty close to zero but not absolutely zero. Birth control pills have over 98+% effectiveness and are the most successful method except for sterilization-- just to give you an example.

This can be normal: It is estimated that successful conception of pregnancy is around 20-25% each time a couple tries per month. However, a couple is not defined as infertile until unsuccessfully trying for at least 12 months or more consecutively. Should that become the case one should see their doctor.

Rare: With a condom and Plan B it would be very rare she would get pregnant.

Anything is possible: But probably not, if she does not get her period at the normal time then she will nedd to check a pg test.