Hello,it is not only number of times you brush your teeth,its the method which you follow matters,consult a dentist get cleaning done and also get educated by the dentist about the brushing technique to be followed. Brushing twice daily doesn't make your teeth sensitive.

Hello First get cleaning done and then do brush twice gargle after every meal Change your brush every three months brush for 2 to 3 minutes

Tooth brushing with the right technique will remove the layer of plaque from the teeth, but the deposits of Calculus cannot be removed by brushing and will require a session of teeth cleaning by a procedure of ultrasonic scaling. If you use a toothbrush with soft or super soft bristles, it will not abrade the enamel significantly and not cause sensitivity in the long run, but a toothbrush with medium texture bristles can. Modified Bass technique is the best brushing technique which is easy to master. Your dentist can explain that to you on a model or you can search for the same on YouTube because it will be difficult to make you understand in the form of text. Cleaning your tongue is also essential for oral hygiene and you should only use your toothbrush for this purpose and not any sort of tongue cleaners. Regards