Did the chronic bronchitis cause my asthma? I had bronchitis for 3 months straight this year and asthma ever since. If yes, then how did this happen?

May be all asthma. Bronchitis lasting 3 months for one year is not chronic bronchitis. Without having all clinical data it is very difficult for me to determine what exactly you had for 3 months. Asthma may develop after infections of the bronchial tree, particularly after viral and certain bacterial infections. If you haven't yet, see an asthma specialist.