OK. So maybe I didn’t tell you everything.

I told you the stuff you might tell a teacher, or a neighbour or the old lady who works at the corner shop and won’t stop asking questions. But I didn’t tell you the real stuff. Not the stuff that counts.

I slide down the back of the door and stare blankly at the jumble of fossils now sitting in my lap. Here are some interesting facts I’ve discovered recently about the animal kingdom:

• The cuckoo is built with a small dip in its back so that it can toss out the other eggs as soon as it’s born.
• Mother pandas only care for one of their cubs, and allow the other to die.
• Shark embryos fight and eat each other in the womb and only the winner is born.

Don’t even get me started on what the spotted hyena does to its relations. Trust me, you really don’t want to know.

What I’m trying to say is, I’m incredibly excited about having a new brother or sister. Of course I am. Babies are cute – in a baldy, screaming kind of way – and a really big part of me can’t wait to meet my new sibling and buy it cute little dinosaur T-shirts and a miniature satchel and (eventually) matching crossword puzzles so that we can do them together over breakfast.

But another part of me is anxious.

Literature, history and nature repeatedly remind us that it’s not always TV deals and record contracts and matching outfits when it comes to siblings. If King Lear and the Tudor dynasty taught us nothing else, it’s that you might want to watch your back. Especially if you’re a half-sibling like me. Because if push comes literally to shove, somebody normally ends up getting kicked out of the nest.

Over the last six months, the baby has started taking over everything:

• First breakfast streamlined into one topic: did you know that the baby’s heart starts beating after twenty-two days? Did you know that by seventeen weeks it has fingerprints?
• Then random questions: do you think it’ll hate mushrooms, like Annabel, or cinnamon, like Dad?
• Then it started demanding olive milkshake and ketchup on ice cream and once – to my absolute horror – a bit of the white chalk from my maths blackboard.
• People started visiting and walking straight past me to ‘The Belly’.
• Annabel started looking tired all the time. Dad started looking anxious and being extraordinarily loud to make up for it.
• And the photograph of my mum on the mantelpiece mysteriously moved to the guest bedroom, as if that would help everyone forget what happened to the last person in this house who tried to have a baby.

Or the fact that the baby was me.

And – bit by bit, gate by gate – the house started changing, and my room started feeling smaller, and my parents stopped talking or thinking about anything else.

Then – without warning – Nick dumped me.

So I threw myself into the thing I’d kind of been neglecting for once: schoolwork. I studied at breakfast, lunch and dinner. I studied in the bath, and on the toilet, and on the bus, and in the shower by sketching maths equations into the steam on the glass. I even studied during modelling shoots, as you already know.

Basically, I stuffed my head with facts and formulas and dates and equations and lists and diagrams so there wouldn’t be room for anything else.

But now exams are finished, and school is over.

Nat is leaving for France.

Lion Boy is still gone.

I’m less important to my parents than someone who isn’t even born yet.

And all I can do is sit in my room, staring at my overcrowded new bookshelves and wondering what to do next.

Because that’s the truth about people with obsessively organised plans: we’re not trying to control everything in our lives. We’re trying to block out the things we can’t.

But now there’s nothing left.

Nothing but the baby.