keeping pregnancy secret till 12 weeks with my 10 years old son fails lol

So this morning I went to the hospital for my early scan, we were in the waiting room and my son was with us coz it's half term and I can't leave him with anybody else. The midwife called us and I told my son stay there and I'll be back, the midwife said he can come and sit somewhere ( the midwife took us to the room with him) can't do anything else coz he was with us now. She ask me loads of question like m I feeling OK, felling dizzy,  bleeding and do u know why ur here  etch, I said I'm here for my early scan. Then she pop the question how many pregnancy u had before including the miscarriage. I said one son which is Jak and 3 miscarriage and now this one, my sons eye opened big and he said to me, why you haven't told me about it??!!!! He was smiling... I was like ooops, we was gonna tell u when it's bigger. I'M BUSTED AND THE SECRET US OUT! LOL I told him not to tell anybody though, hope he keeps his mouth shut lol