Widening Hair Partition

Hello, I am a vegetarian female under 20, and am a pretty healthy person, no allergies or athsma or major illnesses. I HAVE had and still do have very low iron levels and low blood pressure. Within the last few years my hair has gotten thinner and my hair partition has widened. I am growing out my hair for donation purposes and until around June I do not plan on cutting it (perhaps a slight trim). I have been told that this may be because of several reasons including my hair length, the shampoo I use, conditioners, etc. As well, I have split ends and I plan on trimming soon. I use a fine/limp hair "Outrageous" shampoo and conditioner (I also use normal), I never blow dry my hair, and I use natural henna maybe once a year (and have tried the egg yolk thing). I have never died or bleached my hair, I eat plenty of fruits and vegetables (my only lack of a food group is the meat and alternatives group). I don't straighten or curl my hair, generally no damaging things. However, my hair partition is widening and it is bugging me. I've been recommended a drastically shorter cut and repetative cuts (keeping my hair short, etc.) for atleast a couple of years. I was wondering if there was anything natural I could use that would enable me to keep my hair fairly long.