When I was a teenage Christian, there were some things that helped that I'll get into, but I'm also going to touch briefly on things that I wish I knew then that I know now.
What I did that helped:
1. Get involved with a youth group. It doesn't matter if it's from your church or not--you need to build good relationships with other teens who share your belief. It's not only a good support, but it's a very necessary one.
2. Get involved in a legitimate Bible study. Studying the Bible on my own was well and good, but it was much easier, much more fluent, and far easier to understand and get drawn in when I did it with other people. And when doing it, ask questions--even play Devil's advocate. It's important to get to the bottom of everything you belief in.
3. I spoke with my youth leaders/bible study leaders. I expressed my concerns with my faith, how I could hang onto it, etc. Sounds simple, but a lot of the time we thing "I don't want to burden them" or "it's probably not a big deal." You're not burdening them and it is a big deal. They're there for that reason, so take advantage of that.
Things I wish I knew as a teen:
1. Religious and spiritual intellect. My youth group, bible study, and even church did a great job in diving into the scriptures, what God calls for us to do, etc. One thing that they seemed to never do unfortunately was emphasize on the things all Christians NEED to know, such as why Atheism is illogical and wrong, why the world is OBJECTIVE even though much of the world likes to claim it is SUBJECTIVE, why we have free will despite the fact that it is God's will for us all to find salvation (and not sunday school answers like "because he wants us to love him"). Don't treat the faith as "it's true to me, but it's really your thing to believe something else." Indeed we all have freedom to worship and believe as we wish, that doesn't mean God and his teachings are now only "kinda' true." Be a legitimate truth seeker. Learn what is true and what isn't. When you get older, it's going to get right in your face and you're going to eventually say "Enough is enough...what is true, what is false, and where do I stand?" Basically, no more BS (pardon me).
2. You can't please everyone. As a teen, I was very concerned with making sure I was well-liked and didn't offend people. Problem is I did it to a point where I missed opportunities to practice what I believed. It made me a hypocrite. Of course we are called to love everyone, but getting quiet about our religion and faith, especially at times where we need to speak up, is in no way loving anyone. Not only will people have a tough time respecting you when you claim to be a Christian but don't act on it when it counts, but they will also not respect the faith--and who could blame them? Christ said in John 15:18 “If the world hates you, you know that it has hated Me before it hated you." It goes with the territory, but the rewards of sticking to the truth is worth it.
3. The anti-religion/anti-christian rhetoric masked in "logic" is a sham. By no means am I saying this out of annoyance or anger, but the truth is that the rhetoric is absurd. For instance, a lot of people discredit Christianity and God because of the hypocrisies of Christians. It's fair to ask "why?" but to throw everything out the window merely because of the misbehaviors of others is also not facing the truth, but rather saying "I don't like these people, so I guess God isn't real and Christianity is a false premise." Or even when they say "I haven't heard any good arguments for it, therefore it must not be real." This is called 'Argumentum ad Ignorantium' (an argument from ignorance). Because they didn't get a good answer, they feel the other side must be right, but that doesn't answer the question. If I asked an Atheist, "How can God not be real?" and he responded "Because bad things happen to good people," well, he gave a terrible answer, but his terrible answer didn't prove why he's wrong. Don't let them intimidate you into backing away from God, not even a little bit.
4. PRAY EVERY DAY! Not just before meals. I'm deadly serious. Wake up in the morning and pray. Get dressed and pray. Go to school and pray. Pray after classes, pray between classes, pray at work, pray going home, pray before going to sleep, wake up and do it all again. Pray for you, pray for your family, pray for your enemies, pray for everyone and for every reason. Pray that you will grow to know Him more, that everyone will, and pray for comfort an help, and when doing all of this, also pray in worship and thankfulness. You will grow to know Him much more the more time you spend with Him.
5. Just because a fellow Christian does something doesn't make it OK. As a teen, I'd see/hear my Christian friends (or even mentors) saying something, doing something, acting a certain way, and I fell into this trap of "Well if they're Christians, they're infallible, therefore it's OK to do/say such and such." Whaaaa? Don't be afraid to be that guy that says, "This seems wrong." Your friends/mentors who should be setting a good example will notice that someone in the group is standing up for the faith and putting his foot down. Don't wait for someone else to be that person.
This was all I could think of right now. I hope this at least shed a light on some of your concerns. Your concerns aren't much different from most Christian teens. This happens all the time. I remember going to a youth group when I was 15, and the youth pastor was so preoccupied with trying to come off as cool and relevant to us kids that he seemed to forget what we needed to know at that age. I legitimately think the youth pastor cared for us and wanted to help us, but a few of my friends and I were so fed up with it that we left. We felt like we were being patronized as teens and that we weren't being taken seriously. Ever see that terrible movie "Saved"? It was kind of like that. Your concerns are serious. They regard your soul and your life. The good news is you're asking questions and trying to get to it.
Feel free to ask me any questions if you have any,
and God bless you.