I agree..if you hair breaks off when it's natural and relaxed, it could be your hair routine or just your diet! You said you haven't used a hot comb in months, but what about blow driers? Tight ponytails? Products with alcohol in them? You may need products with protein in them to strengthen your hair shaft. Do you take vitamins?
Deep conditioning is a necessity on any type of hair, colored, relaxed, natural - whatever - it should be taken care of!!! I use Ojon Restorative Treatment ... a bit costly...but I SWEAR by it. www.ojon.com
I went from natural for 2yrs back to relaxed, and it has kept my hair very healthy.