It took me two and a half years, due to various circumstances, to be baptised after I initially requested it. God had taken me by the scruff of the neck and given me a good spiritual shake and I was in an all-fired hurry to be baptised, but He had other plans for me. I had been agnostic and knew next to nothing about the Church and the Faith. I spent much of those 2 1/2 years learning and deepening my relationship with Christ. I found it well worth the wait.
There is no hard and fast rule as to how long it takes. I’ve not heard of this mandatory adult 2 year transitional period before. Every parish has it’s own RCIA program and they vary in length. One parish can have a six week course and another, seven months. I’ve never heard of one that lasted 2 years. In addition, some peoples’ circumstances are very different from others. Some might be either agnostic or atheist, others are coming from other faiths like Anglican or Baptist. There is a big difference in what you still need to learn or even unlearn (things which you had believed were taught but which weren’t, in actuality). An Anglican, for instance, could probably make the transition much more quickly than an agnostic. Speak to your local parish to find out what options are available for you.
In the meantime, see if you can get your parent to allow you to be instructed and bring you to Mass, even if you aren’t going to receive the Sacraments, yet.
There is nothing to stop you from reading the Catechism to find out what the Church teaches. It is available in a searchable form online
here. You can look up are various teaching or go to the home page and just start from the beginning (recommended).
Don’t be discouraged, Sometimes the things we value the most were the hardest to obtain. Pray for God to make it happen for you but don’t give up if it isn’t as easy as you thought it would be. I had been taught that Catholics were so hungry for converts that all you had to do was front a priest and he immediately would make a sign of the cross over you and say, “Domine, Domine, Domine, you’re a Catholic, now.”. It was a bit of a rude awakening to find out otherwise but I have never regretted a minute of the wait. God knew what He was doing.
Trust Him.