It's 300 weeks since I was diagnosed, on a bleak day in January 2021. It's 275 weeks since the mastectomy that saw the cancer physically removed from my body, after five brutal months of chemotherapy. And it's just over 225 weeks since the end of my active treatment, including radiotherapy and further adjuvant chemo.

This story should end there: treatment successful, cancer-free, hooray!

Weirdly, it felt as though that's actually where it began. The treatment itself was, of course, grim: the debilitating fatigue, nausea and hair loss of chemotherapy; the indignity of feeling utterly unlike yourself; the early menopause. Not to mention the frightening, painful week in hospital after my mastectomy, with no visitors allowed because of Covid.

But at least I knew what I had to do and I had an end goal. When people asked me how it was going, I'd reply: "There's light at the end of the tunnel."

Then I got to the end of the tunnel and realised the light was a mirage and there was yet more bloody tunnel.

Just as I thought I was approaching "the all-clear" (something I've since realised no doctor says in real life), I had an extremely disconcerting appointment with a locum surgeon. She told me that the risk of recurrence for my type of breast cancer was high, around 40%, and that I should be "very vigilant" for potential signs of it returning.

The good news was that if I made it to five years cancer-free, my risk of recurrence would drop right off. But it barely registered. The surgeon had made it very clear that with my aggressive type of cancer, recurrence would mean secondary cancer, incurable and quickly terminal. I had walked into that doctor's office expecting a golden cancer-free ticket. Instead, I walked out knowing, if the cancer came back, I was likely to die from it.

Now, I'm writing this having passed the five-year anniversary of my mastectomy, with just a few months to go until it's been five years since the end of my active treatment. To say a weight has lifted would be like saying Nigella is quite good at making cakes.

I've been through the deepest depths of fear and anxiety, with panic attacks and sleepless nights a regular occurrence, especially in the first year after treatment. My kids were three and six when I was diagnosed; they're now nine and 12. There was a time when I could barely look at them without my brain being ambushed with intrusive thoughts about how they would cope without me. Now I feel such a sense of gratitude to still be here with them. My favourite days are the ones where I don't even think about the fact that I've had cancer, and we do normal stuff: rushed mornings, swimming lessons, family dinners, watching a movie.

This is slightly complicated to write during Breast Cancer Awareness Month, but I no longer want cancer to be part of my identity. It might seem weird when I've literally written a book on it, but I'm ready to close this chapter of my life.

I still have one final oncologist appointment and two Zometa infusions to go, but for my type of breast cancer, five years is a significant milestone. My risk of recurrence was highest in the first few years and has now dropped right off. The psychological significance of that is enormous.

Here's the annoying thing about having survived something awful: eventually, you have to admit that it changed you in some good ways too.

I became much more interested in looking after my health. Exercise stopped being primarily about how I looked and became something I wanted to do to protect my body. I started paying more attention to what I ate, to sleep and to stress. Not to optimise myself, but simply acknowledging the fact that I have a body worth looking after.

And while I'm not going to pretend I'm now some serene, enlightened person who never gets stressed, procrastinates or wastes time gormlessly scrolling on Instagram, I definitely have a more relaxed attitude to life. You won't catch me worrying too much about whether someone is annoyed with me. There's something clarifying about being forced to confront the fact that life is finite.

I feel lucky to be here, in a very ordinary but visceral way. I'm lucky to be alive and healthy enough to worry about work, money, ageing, my children, whether I've done enough exercise and what we're having for dinner.

For years, I lived with an awareness that life could be cut short. Now, for the first time, I'm beginning to feel able to imagine the opposite: that I might have a long life. That is a surprisingly strange thing to get my head around.

Cancer defined the last five years, whether I wanted it to or not, but it doesn't have to define the next five, or the next 50 (if I'm lucky, and my nan survived breast cancer in her 40s, ultimately living to 98, so there's hope!).

I spent years thinking about how long I might have left. Now I want to think about what I'm going to do with the time I have. Five years after my mastectomy, I finally feel ready to stop being a cancer patient. And start getting on with being me.

Rosamund Dean is the author of Reconstruction: How to Rebuild Your Body, Mind and Life After a Breast Cancer Diagnosis