pregnant at 16

I was 16 and a sophmore in highschool and my boyfriend and I were at a party for New Years and when we went back to his house he went and got some orange juice and gave it to me. it tasted a little funny and he said that he had just added some vitamins and that it was ok to drink.. I remember finishing the glass of oj (at about 10 o’clock) and dont remember and thing until morning and when I got up he was lying next to me on the floor.. about a month later I was at a friends house and was getting ready to go to a birthday party for another friend, we went to the store to get him a gift and she bought a pregnancy test for me because I had missed my period and was felling like crap… we went back to her house and I took it and it was positive.. She told me that she believes that my boyfriend at the time drugged me and raped me.. could you tell me if this could be possible… I am currently with a new boyfriend who does not do drugs or drink.. and I am a senior (18 yrs) in highschool…… Thank you