I think you are doing the right thing by making sure he has protection, better than dealing with a teenage girl standing at your door pregnant or him getting something from someone, i say to my nephew dont do a thing unless its wrapped up! he just looks at me strange lol but gets the message

Sorry to hear he is sneaking out, such a worry for you, my nephew who lives with us didnt call me the other week and didnt come home till 9am, i was so worried as he always rings me to tell me where he is! he did say sorry when he seen how worried i was though, got his year 11 report card today, he did pretty well with a's and b's mainly and a D in maths.