Delay in period after sex. Her period.

Me and my girlfriend first time we had sex last month 26th first we had a intercourse using condom i dont have any feel so i removed the condom. I have washed my pennis using soap amd viped with dried towel and i have applied oil on pennis and i inserted without condom to feel how it is and we have sex for 2 to 3 minutes at that time no ejaculation and no precum also. After that i we had sex using new condom and i have ejaculated in condom itself. 22 dec she had period on 26 dec it stopped so we had sex on last day of her period...today date is 27Jan still she dint get her period...we have tested using pregnance teter today morning tat is negative...whther it is normal to get delay in period 3 to  4 days..please let me know is ther any chance of preganacy.....i have ejaculated when using condom only i have checked at that time whether the condom s broken but it dint broke. She took Meprate table for 3 days still dint get her periods..