There is no telling the limits of God’s Mercy. If you are not given the chance to confess in the form of the sacrament before you die…The Lord alone knows your heart even better than you. Trust in his Mercy.
Think of it this way…if men are in battle and they see that their brother (in the eyes of a soldier, all his fellow soldiers are brothers) is about to fall to his death, surely the true friend would do everything he can to save his brother even if it means giving his own life. God’s love is greater even than this, for He gave himself to us on the cross through Jesus His son, Our Lord.
Also, make sure that you develop a good devotion to our Blessed Mother, pray, pray, pray…go to confession frequently (once or even twice a month) be sincere about your contrition and obey your confessor…then, you won’t have to worry about it.
May God bless you!