It could be that you need more practice. MUCH more practice. At a guess, how many hours do you drive in a week? Can you repeat your driving instruction? (From a professional instructor...not family) How about Driving Simulators...do you have access to them? They are a good way to safely and inexpensively log some driving time.

You need practice staying in your lane, making turns at intersections smoothly, obeying signs and signals, and most importantly, anticipating and reacting to the bizarre crap that other drivers do every day. It just takes lots and lots of practice, until you can act and react automatically without having to take the time to think about it.