Help please!!

So my boyfriend and I had sex for the first time yesterday but what I didn’t realize is that it was still during my fertile window according to my app. I had been put on birth control pills a few weeks before this and the day of, I had taken my first placebo pill. It was in the heat of the moment and we didn’t use a condom but it was only for a few moments and he didn’t cum. How high are the chances of me being pregnant? What can I do?