You can attempt to whiten your dentin first. A little may improve but not enough will make you satisfied for long term. Lumineers veneers without prepping your tooth away more will be best option to achieve that brightness and to protect your teeth.
It is not unusual to have pain after in office whitening. In addition to what you are doing, I would try rubbing some sensydyne toothpaste 2x daily on the sore area and don't rinse or drink for 30 minutes.
I have found most of the time that calcification spots tend to get whiter with teeth bleaching. That being said, there are other options such as post bleaching bonding or MI paste.