Kirsty Bosley: Ringing the changes but still keeping my call cool

Up until last week, I thought I was pretty cool. I had an iPhone 5 and knew how to download things like movies and music and take selfies. I had apps that let me text my pals for free and I knew how to send little smiley faces of all skin tones.

My digital world came crashing down around my ears, though, when my phone contract was up.

I had my sights set on the new iPhone, because I've been on that Apple hype for years now and I just get it. I was superior, technologically. I was IN with my iPhone and all of its pros. Like Siri, which I'd never used (but I was comforted knowing she was there).

However, one trip to the phone shop reduced me to an overwhelmed state, looking at phones big and small. Did I want an iPhone or a Samsung? Sony was another option. Did I want a tablet? How much 'gigs' did I use? What was I looking for in a handset?

Within two minutes of being in the shop my brain exploded and slowly began to trickle out of my ears, down my neck and into the collar of my shirt. I only wanted a phone, and instead I felt like I was set to make one of the biggest decisions of my adult life.

I'd started to focus on the word 'tariff' as it came out of the salesman's mouth until it barely made sense any more, just like the word 'must' did when I had to write the lines 'I must not talk in class' for an hour in year 9 detention.

I must not talk in class. What tariff would I like? I must not talk in class. What tariff would I like?

It might be a smart phone I was after, but I felt anything but smart when faced with all of these options.

At 27, I assumed that I wasn't 'down with the kids', but that I WAS 'the kids'. It turns out that when faced with a plethora of phones that can do snazzy things like read your fingerprints and track your heartbeat, I'm not a kid at all.

At what point did that change? When did I go from being in the switched-on cool gang, to being someone that asks: "Can I do ringing people on it?" to a phone salesman?

What started off as a basic trip to upgrade my handset had turned into a midlife – or rather thirdlife – crisis. Is there going to come a day where I look in the mirror at myself and think 'I just can't pass off this Iron Maiden vest any more'?

Will I one day go to fistbump someone and they'll laugh at me for doing so? What moment marks the move from cool kid to stupid grown-up? When someone younger than me refers to me as being 'your age'? I can't lie about this, readers: I am deeply concerned.

I myself split society into very basic groups: kids, us, moms and dads and nans and grandads. With so many of my friends now getting married and having kids, am I in the 'moms and dads' category?

In a desperate attempt to hold on to my cool factor, I chose the newest phone I could get my hands on. It's £50 a month, but if that's how much being cool costs, then I consider it a bargain.