advice/ help/ answers

I'm about to go for my blood test for acutane, they'll ask me if I'm pregnant and I have said no obviously, they followed asking if I'm sexual active and I said no. But I am. Reason being is I'm 16 and my boyfriend of 2 years have tried it a few times and my mum doesn't know about it and I know she will 100% flip about it! Will the dermotologist know whether I've had sex or not just by my test? And if so will she tell my mum! I'm so nervous she can't find out