How likely can you get pregnant with on ovulation day only?

I'm not charting my cycles or anything. But Saturday night I noticed egg white mucus and my husband and I BD. I think I was ovulating because I was having loads of cramping, tenderness, etc. Yesterday I bought OPK's and I used one today and yesterday and both were negative. In fact the test line was there but light. Could I get pregnant if only having on that day which was when I think I ovulated. And it was late too. Do I still have a chance or did we BD too late? Thanks!