Spurs went into the break a goal down and needed Defoe to pop up with an equaliser and earn a replay at White Hart Lane.
"We should have won it in the end," the striker told the Spurs website. "We had a great spell in the second half when we were fantastic.
"We had a bit of a rollicking at half-time and we deserved it because we didn't compete in the first half.
"You know it's always going to be difficult at Bolton. You have to compete and the rest of the game will then take care of itself, we know we'll always create chances.
"First though, you have to compete otherwise a team like Bolton will get on top and that's what happened in the first half."