I recommend starting to use Herbal essences shampoos and conditioners (I personally go with Aloe Vera ones). There is a line that has no dimethicone (and any other silicones), no sulfates and salt either. They are 98% made of natural ingredients and although getting control of your hair takes a while it also is worth it.
But check your vit levels as some girls mentioned here as it could be caused by defficiencies!
Also, there are needle rollers which stimulate hair growth (I use them on my face for wrinkles and I can confirm that along with reduction of wrinkles they improve my mustache

, in a way that is not desired iykwim). Other than that I think collagen can help. There are various threads here that mentioned which are the best etc. It's known for improving skin, hair and nails
