when i was about your age i struggled alot with almost exactly the same thing.
i was born in a family that believed - well partly; my mother did - and my grandmother on my father's side had devoted her whole life to Christianity; she was a missionary for decades, always travelling the world spreading the gospel. but my father, i don't think so, and my grandparents on my mother's side seemed to just give it lip service, but i don't know.
anyway i was brought up in christian churches. ever since i was a baby. it wasn't the only 'religion' i knew, but it was what i was taught my whole life.
so i started wondering -- about the same age as you are -- whether i really believed at all, and whether i only believed because i had been more or less 'indoctrinated?'
it's impossible to escape my past though. it's already happened. i prayed about these things, and i ignored these things to see if they would go away -- and God gave me signs. things that were meaningful to me. in dreams, in pictures, in circumstances, in words and understanding. not 'fire from heaven' but meaningful, very personal things, that were beyond coincidence -- things that only someone who knew all my intimate thoughts and controlled every slightest nuance of the whole universe could have organized. things that no one else might notice, not like the sky tearing open -- and i think, this, because He wanted me to believe without being 'wowed' by miracles. because that's false faith; another big light show comes along, and maybe you believe that. or you always need the earth to quake for everything to be real somehow. this isn't how He operates -- for His own reasons.
one day i realized, and accepted, that even though i had been brought up in the church, this was purposeful. if God controlled the entire universe, and my whole life, then it was Him who caused me to be born into just this family and to receive all these teachings since i was a baby. This is a blessing -- not a curse! not everyone has such an easy path toward believing and trusting Him.
God organized my whole life -- and He made it so that from childhood, i heard of Him. i've always needed things to be pretty darn obvious before i trust them, and He made my life just so.
objectively: if i believed that God must exist, and i did, and that God must be in total control of my experience as a living being, and i did, but then i denied the things He had brought me up in, the gospel that He caused me to hear, then wasn't i denying the first two principles?
He had put in me this nature to examine other beliefs, and find them all coming up short - and He had put in me this gospel, that i never found coming up short. sure, i found the way that some people taught or explained it to be wrong, or to come up short -- but the Jesus Christ who is in the scripture, i could never poke a hole in. The only objection i had to this was that God had organized my existence so that i would have a knowledge of Jesus ever since i was a toddler. So i was going to fault Him for that? the God that by assumption must be have organized my existence?
i understood then this was temptation and confusion by the evil one -- and that i did believe, but my faith was small, and that God had chosen me to believe, and even chosen to give me this doubt so that in the end my faith would be strengthened and grow.
