I've never had HT and never had a hot flash. But I still have something to contribute here.
When my wife first started getting them, just like you, she was curious to know how many and how often she had them. Rather than leave it up to chance I taped a small data logger (the size of 5 dimes) to the inside of her bicep. I used the
Maxim iButton DS1921H and programmed it to record time and temperature every minute. It also recorded the time the when the temperature exceeded a certain value. The unit is waterproof so she could wear it all day and it stored about
2000 minutes of data (~30 hours) before needing to be erased. It worked great.
I forget. Did I say my wife was a saint?
J