What a wonderful question!
I like that its certainty you want to get to, not to just 'believe' or 'have faith', but to 'know'. That's like the end game.
From my journey i'd say most people with an interest develop their 'thinking' through experience, like hearing testimonials, over coming challenge, having powerful feelings, being touched by words, in parables or songs or through a feeling from worship etc.
God as a creator is disputed, by me too at your age. But a creator is quite scientific in my view. Big bang or not, it still had a cause. All matter came from somewhere, like pure energy perhaps, set in motion.....
I also wondered that, whatever the cause of matter, space is made of 'nothing'. How do you scientifically create nothing - and so much of it!
I have read stuff from many religions though i call myself Christian because I'm awe struck by Christ. However, from personal experience, I'd caution about trying to understand the old testament in a purely literal sense. It can become confusing and be a distraction to a modern logical thinker in SOME instances. eg creation. There are wonderful lessons in the old testament though, like Job, telling us how life's hardships are an opportunity to be rewarded, but we won't know when our good 'karma' will come to us. Don't be tricked by time lapse between do good get good, do bad, get bad. You gain a bit more insight as years go by and experience shows you more of both sides of the coin. Transformation is an underlying theme, and the source of true Happiness is a good question to ponder. Find a church you like with good teachers. Romans is a recommended starting point in the O.T.
Yoga & Buddhism consider the nature of God. This includes "Bliss Absolute & Knowledge Absolute" from this condition creation seems like a good idea. As for how we see it, look at how you feel when you create something.
Anyway, i might say that discovering God through life is The Beautiful Game. And the best tip is Action, actions that you feel build your heart, as selfless as possible - you don't need to worry that altruism may not exist, just try to practice it.
You need never stress any of it. God is perfectly happy and nothing you can do will make Him more or less so, or make Him love you any less. Tat Tvam Asi