I do have to say though, Dot, that I give you kudos for being honest. I've grown up in the church all my life and have found that many good Christian people are thinking the exact same questions you ask about sex but are afraid to say anything or have no one to ask. I've heard it stated before that if people were more willing to talk about sexual issues within the church, fewer people would be turning to sources outside the church for answers. Of course, there has to be a balance, but somebody also has to step forward and be willing to take a risk.
I commend you for always being honest with your questions.
I don't want to repeat what others have said here because there have been some excellent posts--however, I feel the need to also point out that if someone is struggling with strong, verging-on-the-edge of out-of-control sexual desires, asking God for help in getting them under control may be the very first step that needs to be taken... and it can take a long time.
Keep in mind, marriage is not a guarantee of sex--when I was married, my husband and I went through plenty of no-sex times due to anger, whether he was angry at me or I was angry at him, and at one point, we even lived at opposite ends of the house for many months. It was a tough way to live. I understand the Biblical principles of "not depriving each other" but in reality and in most marriages, it happens for one reason or another (also consider illness, stress, etc.) If your spouse does not want to have sex or can't, and I can guarantee there will be times when it will be that way, so guess what... You're back to square one--not having sex! And this time you'll be married, so there are no other options except to ask God for the grace to live through it.
It's also important to remember that if one spouse has a very high sex drive and the other does not, there will be problems, and often a divorce, if both aren't willing to find some kind of compromise.
I can tell you that you aren't alone in your thoughts. When my husband left me, it was VERY hard to adjust to a life of no one there and a complete loss of intimacy, both mental and physical. It's been even tougher on me to know he's remarried and I have not--knowing he has those things again and, with someone else. I sometimes become very discouraged and upset. BUT, I know God has worked with me and changed me over the years... And pointed out several areas I needed help with, including the areas you often speak about. I was way too clingy, needy, and insecure, which translates into several areas of our life, including physical intimacy.
Keep seeking God, find things you love to do and are passionate about, and reach out to other people... I know you've said you are extremely shy... I pray that God will send you the right people in your life to help you and that you'll have the courage to let seek them out.