Have patience it's Christmas, more people will be around later in the week.
I think hair loss, especially gradual loss, is probably more of an internal thing. Yes product build up or a dry scalp or an allergic reaction can be behind hair loss, but I think diet, genetics, and male pattern baldness are more liking culprits of thinning over time. Genetics...well there is nothing you can do about that, but diet is a huge one. Hair is probably the least important part of your body, so if you're not eating enough fruits and veggies it's not going to grow very nice or thick.
Pay attention to the hair your losing, is it breaking off or is it more like shedding. Dry hair breaks off. I have sensitive skin so I try to stay away from non-fatty alcohols in products.