Your very well spoken for such young person. Your no doubt very intelligent but one thing you do not have and can not have at your age is life experience. You can't possibly know how bumpy and twisted that road is until you've travelled on it for quite a while and that's once "you" are driving and not just along for the ride.
You have many, many years ahead of you to fulfill all kinds of dreams. You are but a child that is thinking of getting another child. Imagine if you were to get pregnant now or get a girl pregnant now (sorry I don't know if you are a boy or girl?) and had to become a parent at your age. It would be overwhelming and something you will need to deal with for the rest of your life. On top of that the "child" you are thinking of getting is never going to grow past the age of 3 and is "never" going to move out. This child is going to need as much space, time and enrichment as you do. Not just a cage.
Live some of your life first and get those all important experiences under your belt. Become independent, stable and have a much more defined path before you make this life time commitment. You are going to want to meet and share your life with a special person also. This bird will be a factor in that even happening. There is no rush to do this because you are so young.
You just don't know what you don't know until you know. A lot of us old farts do know because we've been there, done that.
You sound like a very committed person but there is no rush.