The pre cum (pre ejaculatory fluid) is mainly composed of Seminal fluid & Cowper's fluid.
It is similar in composition to semen, though there are some chemical differences.
However, studies have found low levels of sperm in this fluid.
So, even if this pre ejaculatory fluid (pre cum) enters into the genital tract, the sperms present in it can fertilize the ovum, resulting in pregnancy
But the chance of occurrence of such an event is less.
There is no need to worry, you can wait till your periods.
If they are delayed, a Pregnancy test can be done to confirm it.
In case of pregnancy, it will give a positive result within one week.
Wishing you a Good Health.
Let me know if I need to clarify further.
Thanks & take care.