How do you get to know that where your strength lies in engineering?

What does computer science and computer engineering comprise of? Done coding quite a few time firstly, some at code org in 6th grade and then at codecademy in 9th. Always wanted to be an engineer, that???s why took the non medical Stream for 11th and 12th (in India). Till now, just studied the regular subjects till 12th and a whole lot of science to pass the entrances (weren???t that good). How do I know that I???m going to regain my lost confidence ?