Hi Thanks for your query. Thinning of hair is related to the growth at root level. Straightening etc cause hair shaft breakage. You can use protein based conditioners to give volume to your hair.
Next Steps
Following health feed should be helpful
"Top Causes of Hair Loss and Hair Thinning in Women" by Dr. Jolly Shah Kapadia - https://www.practo.com/healthfeed/top-causes-of-hair-loss-and-hair-thinning-in-women-15052/post
"How to Reduce Hair Loss: 25 Easy Ways!" by Dr. Jolly Shah Kapadia - https://www.practo.com/healthfeed/how-to-reduce-hair-loss-25-easy-ways-25454/post