Suggest Treatment For A Delayed Period

So me and my girlfriend decided to try sex, but we just rubbed our parts together without a condom, I didn t ejaculate in her what so ever, but I believe I did pre ejaculate and I m kinda nervous cause she still didn t get her period though she did get the cramps (we did this on the 26th) then another time about less then a week ago we played around but it was on her behind, I noticed that what I think was precum was on her vagina lips and I wiped it off immediately just in case that was our last time doing that since she went on vacation, but she usually gets her periods around the ending and beginning of a month, and she hasn t gotten, the period yet, please help I m nervous