Faye,
I've just found out that you can ovulate pre-menopause and therefore can have a PEAK on your monitor.
I get PEAK readings on mine and have just had blood tests results to show that I am peri-menopausal. This means that from 2 years to 10 years time I can expect to go through the menopause. It shows that my body is perfectly normal and doing what it should do at my age (I will be 47 next May and my mother went through the menopause in her 50's).
My CD21 results show that I am ovulating, but my CD3 results have shown one result that indicates my eggs are either diminished quality or quantity. I've been prescribed Clomid to try to increase the quality of ovulation. It's worth a go I reckon.
It's important to note that women can go through the peri-menopause at any age, even in their 20's. But it is most common after 35 and THE most common after 45. These are rough figures as we are all very different as you know.
Hope this helps. I would suggest having the blood tests done that I did as I am now aware of what my body is up to.
Footnote: These FSH levels fluctuate somewhat too and apparently they can be high one cycle and low the next in the same woman. The fact that they are high once is enough for me to confirm that my time is running out. So sad, but true.