What are your thoughts?

I am 32, just had a tubal reversal July 23rd. This is my 2nd cycle since surgery and was given the go ahead to TTC. I have 4 previous children and never used anything to time conception so this was my first time using opk. I have been using them since the first day after AF. I am on CD 13 today. Yesterday was CD 12 and I had a positive LH surge. Today it's negative. My question is..... If hubby and I BD'ed cycle day 11 and 12(very early morning on both days), I had positive surge CD 12 (in the afternnon), and I should be ovulating soon, what the chances of becoming pregnant if we don't BD again? Is it possible to become pregnant if you only BD 1 and 2 days before ovulation?