Whst my chances on getting pregnant when I sex2-3 days of my ovulation and on the day of

Highest chances are the two or three days before to allow travel time, but of course pregnancy can happen any time of the month. It is just a high percentage, no percent can be given or guessed at, since factors of sperm and egg health, and just luck ( good or bad) comes into play.

The estimate usually given is about 20-25% for the reasons Fr_Chuck stated. Timing is only part of the equation, hence why the odds are not higher.

The next question would be, how did you determine when your day of ovulation was? If using the online calendars, it is important to remember that they are not automatically on target for every woman.