I would say "yes" Aikido is an excelant tool to have for self defense. One among many though. You must also have a mind that is aware of its surrounding, and always be mindful of yourself and your own body( i.e. your breathing, stay calm, stay relaxed), always be AWARE.
But, having said that, Aikido is also an exelant way to help develop and enhance the awareness that i have just described
And, as for me, Aikido work's exelantly for self-defense. And i started when i was about 16 too.
But, be mindful of the school you join, check it out first. Not all Aikido schools teach Aikido. If that makes any sense.
I'm not sure if i helped any. But that is my take on the answers to your questions.
Feel free to ask questions!! ALWAYS!