The sure shot orgasm is not by your dick, its by right use of your lips, tongue and fingers. Play right way on oral, its a sure shot. Use your mouth on her clit and pussy lips, insert two fingers on her pussy and move in oout slowly with pressure on frontal pussy wall.
In your last question 3/4 weeks ago you said you are 21 she is 38 and married, is it the same lady? Go ahead champ. You are scoring well. Make sure she reaches orgasm before you start vaginal penetration.