I'm 17 and I noticed my period hadn't come. I asked my mum to buy me a test, we took it together (I mean i peed and she timed). She wouldn't let me see until time was up so I went and sat down, she came in and said "Sorry darling, it's negative." A few moments later she let out a big laugh and said "Nah, you're pregnant! Congratulations" and we hugged and cried and danced around.
I don't understand this whole "my mum threw me out the house", "I was so scared I hid it for 6 months"... My mum couldn't be happier and I never expected her to be otherwise. Shouting or getting annoyed won't change a thing, it will just add tension and stress to an unchangeable situation, why not just be supportive from the get-go instead of huffing and puffing for a few months and then being happy and helpful later? (Comments she's made about mothers of my friends with children) She's always had the attitude that everything happens for a reason and God gives you what he thinks you need, even if that's a tough lesson.