I agree that you may be doing more damage. We would need more details as to how you are creating the bun.
When I do my buns, I will either have a part on the side, in the middle or no part. I will either wear a low low bun, a side bun or a middle bun. I also will twist my hair like I'm about to do a bun and make an figure eight and put a banana clip on it making sure my ends are tucked in. I also make sure to move my buns around and I do not use a brush at all ever. I use pomanade and serum on the edges along with a fine tooth comb from time to time then the silk scarf technique to make it smooth. When I am around the 8 week post touch up I try not to use the fine tooth comb as much and this has allowed me to stretch out my relaxer to 16 weeks and gain mega growth as well as retain my length since my ends are always protected.