he he ...Your words make me very awkward at first ,But I come to answer the question ,I am a Chinese ,I want to explain first ,Translating and becoming Chinese in English has very a lot of writing methods ,I give you several choices ,The first :妈,我性交了。But this kind of writing method lies in us seems,It is very awkward to read ,So I help your writing another and read not to stand up awkwardly ,The second:妈,我做爱了。Have been replaced two Chinese characters the middle this one ,We Chinese say those two Chinese characters are “make love” in English ,If you need sentences more implicit ,We can say:妈,我上床了。In fact all there is awkward some in our view in three sentences of above ,Because the few targets in the sentence ,Such as :"Mom, I had sex with sb",Chinese is“妈,我和sb性交了。”Read on very well like this ,It is all right that other two yous replace corresponding Chinese characters ,My English is very bad ,Educate my English if having time ,Good luck!