Help please

Sam

Is it possible to have gotten pregnant from my boyfriend slightly inserting his tip into me? He had some precum on him and im kind of worried because i was supposed to have my period last week or so and i only had a few spots of blood. The interaction was around the 27th of may and i have not had my period since. ive also been getting headaches and nausea, and my stomach hurts when i lay on it at night