Perhaps my colleagues will offer a different take, but mine is, there is nothing more important than prayer, even school work, especially if it is helping you avoid serious sin.
Jesus said in the gospel reading today:
"You have heard it said 'You shall not commit adultery', but I say anyone who lusts after a woman has already committed adultery in his heart. If your right eye causes you to sin, tear it out and throw it away. It is better to lose one of your members than have your whole body thrown into Gehenna. And if your right hand causes you to sin, cut if off and throw it away. It is better to lose one of your members than have your whole body thrown into Gehenna."
I don't think he meant the [tear out-cut off ones] body part suggestion literally, but it does convey the seriousness of sin and the directive to re-order our lives in any legitimate way in order to avoid it.
My advice is to try to relax when you pray. Don't worry about other things that need to be done. Remember the Martha/Mary story in the Gospels. Pray from your heart as a way of loving God. He will return your love with grace and peace.
And always remember, if you ever fall, Jesus always awaits you in the Sacrament of Confession and Reconciliation.