I am perimenopausal and I have not got my periods. Am I pregnant?

Hello doctor,

I am a 46-year-old female and my periods have become increasingly irregular. They used to be around 24 days in length but my current cycle is 36 days. My basal body temperature indicated that I may have ovulated on day 10. But I have not menstruated at all this cycle - not even spotting. Late last week, I had slight cramps and pains in the regions near my ovaries, which made me think that perhaps my body was trying to ovulate again. I have taken a pregnancy test, which was negative. I do not believe I am pregnant; rather, I think I may be entering into perimenopause.

I have been trained for a marathon last year and during training, I ran up to 31 miles or more per week. I had a cycle of 36 days. However, since that time, my cycles have been as short as 14 days but no longer than 31 days. My partner and I use condoms and I track my cycle so that we do not need to use these on infertile days. However, given the length of this cycle, I am unsure whether condoms are necessary until after I have menstruated next. My question relates to fertility in this perimenopausal stage. As I believe I ovulated on day 10, does this mean I remain infertile until I get my next period? Or is my body going to ovulate again, meaning that I will again be fertile?