The number competing for an appointment really varies state to state and district to district. I know of some districts that have over 40 apps. and I know one that had just one app. The best thing to do, (and I know you don't want to hear it) is forget about other people and just do your very best.
Your application not being the best of all the apps does NOT mean you have no chance. For instance, suppose you and a guy named Kyle both applied to senator #1 for a nom. He has better scores etc, but he may go on a nomination from senator #2. There are a lot of factors that play into these things.
Last, not being asked to come in for an interview does NOT mean you will not get one. I applied to both of my senators and my congresswoman. My congresswoman and one of my senators interviewed me, while the other senator did not. In the end, all three of them nominated me. (My congresswoman gave me 2 noms.)
If you are still wondering about an interview, CALL! Don't get your parents to, don't get your friend to, and don't get your dog to. CALL THE OFFICE YOURSELF! That will not only answer your question, but will show that you are very interested in obtaining a nomination. Hope this helps.