Yes, pregnancy can happen even without full ejaculation because of pre-cum. Please consult a doctor for proper family planning and safe contraceptive advice.
I have been reading a lot about this and yes, pre-cum can contain active sperm. It is surprisingly common to conceive this way if you aren't tracking carefully.
According to the tracker apps I used, pre-cum during your peak fertile window carries a high risk. Better to log your cycle details on an app to stay sure.