I Am 45. My Periods Are Usually About 1 To

I am 45. My periods are usually about 1 to 2 days in length and even then the flow is very little. On the first day of my period, I barely shed any blood and I had unprotected sex and now the period has completely disappeared, which isn't always unusual. It sometimes does that and then starts again a couple of days later and lasts for a day or two and then is gone again until the next cycle. How likely can I get pregnant during this situation and time frame?