My sister and I are not best friends. Still, she knows me better than anyone.

• I grew up playing parallel to my younger sister, Hannah.
• For years, I wished her bond with my sister matched what I imagined sisterhood to be.
• After hard life events, I learned to value my friendship with Hannah for our history and loyalty.

I recently asked my mom what my younger sister, Hannah, and I were like together when we were little girls. "You played parallel to each other," she told me.

This didn't come as a surprise, because as a teenager, I remember it exactly this way. Living parallel lives together as sisters.

It was only ever the two of us, and with our ages so close together — I'm not even two years older — you might think we were inseparable. It just wasn't how it was.

We were so different

We were night and day different then. I woke early; she woke late. I was out with groups of friends at every opportunity; she had a couple of close friends she was content to see occasionally. I was meticulously tidy; she was unabashedly quite messy (we shared a room, so this posed problems).

The list of differences was endless, but one thing we both had in common was that we could wind each other up as no one else could.

We also both liked the series "Pride and Prejudice." Many afternoons were set aside binging the Bennet sisters' woven-tight relationship. I remember thinking my sister and I weren't like the Bennets at all. They depended on each other in a way Hannah and I didn't.

When we went our separate ways in college, I rarely contacted her, and she rarely contacted me. Occasionally, we'd send each other a text, but other than that, we just saw each other briefly on the weekend at home or during the holidays.

I moved to the UK

Once we finished college, I moved to the UK to marry a Welsh man, and later settled here to raise my family.

It was around this time that social media began to take off.

I remember watching videos, reading articles, and flicking through pictures of sisters on Facebook who were what I'd describe as "bosom friends," thinking I wish I had the same with Hannah.

It was also during these early years in Wales that I felt desperately lonely. I craved deep, abiding female friendship, and thought that if only Hannah and I were closer friends, perhaps I wouldn't feel so lonely.

If we texted and phoned every day, sharing our deepest, darkest secrets which no one else knew, and lived in each other's pockets, that would fill the friendship void.

I imagined sisters all around the world had this kind of intimate friendship, and we were just missing out. Where had we gone wrong? How did we miss out on what sisters everywhere were experiencing?

And then I hit my 30s.

My sister was there for me

During this decade, there have been some significant events in my life that have nearly broken me. And one of the few people who was there throughout was Hannah.

Hannah checked in via text consistently. She came and visited from the US, eventually moving to London for work three years ago. Now, we see each other four to five times a year. She's taken phone calls where I have just cried.

She shows up, over and over again.

Not just for me, but for my three boys. Being involved in their lives is of utmost importance to her, and because we don't have much family around, of utmost importance to me too.

Although I have friends, I have no friend who is quite like my sister.

We still aren't what I would consider stay-up-into-the-night-talking-endlessly friends, and are still completely opposite in so many ways, but I've come to realize that my sister really is the closest female friendship I have.

She knows my history in full. I know hers. We've walked — even if in parallel — with each other since childhood. No one else knows her as I do, and no one knows me as she does. If something were to happen to my husband and me, it is Hannah I would trust more than anyone with my children. We can fall out briefly, but never forever. She'll always be there for me, and I'll always be there for her. We're bound together.

Sisterhood isn't a one-size-fits-all. Each of our sister bonds is unique and doesn't have to look like the others. It was only once I accepted and believed this that I could fully appreciate the eternal relationship I have with my sister.

Hannah and I still live parallel lives. We certainly aren't the Bennet sisters, or giddy besties who do every single thing together. But neither of us is going anywhere. Sisters forever.