Since you have studied for years and I don't really know you I am going to be brave and ask you some questions I have always wanted to ask. But didn't want anyone to know how dumb I am or maybe that I wasn't saved. I have always lived with this fear.
Believe me, I know EXACTLY how you feel. Often I would not ask the questions that bothered me for I also didn't want to appear dumb. I would often think of the saying, "It is better to be quiet and to be thought a fool than to open your mouth and remove all doubt." :) I, instead, learned to listen carefully. I got used to having many, many unanswered questions. It turns out that my situation drove me to find things out for myself. I picked many things up just by listening more carefully than even those who were doing the talking. I found out that most of them really didn't have a clue! You are not alone in this. And know this: it may not seem like it, but it is for your good. :)