There are many pleasant things about being sterile. There's the children thing, obviously. And the fact that every couple of years someone will pay you £600 to tell your shocking story to the readers of their women's magazine who have obviously forgotten you since they last read about you somewhere else. But my personal favourite is the sense of inner peace and beatific calm that settles upon you when you are able to finally let go of the constant low-level fear that is worrying about the tardy arrival of your period.

No more tearing of hair, no rending asunder of clothing, no praying to gods both major and minor for the damn thing to arrive immediately and deliver you from days spent discussing silicone versus plastic teats on a brownfield estate in Amersham. Or in my case, being forced to watch Loose Women from a TV on the ceiling with my toes pointing skyward as a doctor sets about my business end with a the upholstery attachment from a Dyson. No. You can trip frivolously about town with a sunny disposition and a tinkling laugh (though possibly not in light coloured clothes), safe in the knowledge that whatever else Auntie Flo might be doing, she will assuredly turn up sooner or later.

The downside of this of course is that I have no need to keep any track of even the general kind of time in which this might occur. Which means I no longer know when I'm premenstrual. If I was the kind of woman who raged and snarled, ate black forest gateau with a potato masher and constantly fell off the back of chairs when her period was due, it would be obvious. But I'm like that all the time. The only way I can tell is because my sense of taste, never all that much to begin with, slips quietly but firmly into the twisted bowels of lunacy.

This time, I bought a bag. It is large and it is green. It has one diaphanous maw at the bottom of which you cannot find anything and six tiny pockets that could only be of any use if you're the kind of woman who cannot leave the house without lipstick. It has a collection of woollen pompoms and clattering brass trinkets hanging off it that let friends and colleagues alike know where I am at all times. It is lined with carpet from an episode of George and Mildred. And it is made of moss. I can never go near another goat in my life. Not that I do so on a regular or even incidental basis, but now that I actually can't I find myself disproportionately agitated by this seemingly easily avoided curtailing of narrative possibility.

The time before, I bought a yellow satin prom dress that made me look like a slab of melting butter. And 2,500 ear plugs that I then left on the bus. Despite my almost constant hectoring, the major pharmacutical companies seem curiously reluctant to print DO NOT GO SHOPPING on capsules of Evening Primrose Oil. In league with the retailers, I don't doubt.

Still, better than that time I bought some salad.