I used to have pretty bad sensitivity to brushing my teeth. It went away with time. My advice would be to be gentle but not to fixate on such light touches and bumps.

For a time I also found it helpful to brush my teeth only right before going to bed (and, of course, being extra thorough). That way I wouldn't be thinking back to the morning tooth-brushing throughout the day.

For sensitivity to bumps in general, cardio exercise and an anti-inflammatory diet can be helpful.