You may google 'male deer exercise'. Do this exercise twice a day.You will get the result in 15 days. You may ask your girl friend to do female deer exercise after you get married. wish you a happy married life.
This is a usual fear with every person who gets married. wetness of glans is normal. This is natural lubricant for penetration. woman also gets wet in her vagina. So you need not worry about wetness.
Habit of masturbation is normal. It does not harm if it is done to satisfy the natural sexual urge.As you are already know the girl, you will not be nervous with her. It is possible that you may not be able to enjoy in the initial stages. With little practice, you will be OK.It is better to focus on other aspect of marriage, rather than sex only. Gradually both will be adjusted to each other in sexual act.