Help! Dry and Dread-like Curls
So I've been having some issues with my hair for the past couple years. I find that after a couple days, my hair becomes very dry and separates into chunks (almost like the beginning stages of dreads); several sections seem to rope together, leaving my hair weighed down with less volume and more of my scalp visible (I hope that description makes sense...). At first I tried switching up my products, since I had been using Garnier leave-in conditioner for years and years; I've been using Herbal Essences Long-Term Relationship leave-in for a little while now, but it hasn't really made a difference. Then I tried cutting my hair, which I wanted to avoid at all costs, but I hadn't cut it in about 4 years, so I figured it was time (I cut it myself, and I've never been to a salon); after cutting about 3 inches off (my hair originally reached my mid/lower back, and now it comes to about 2-3 inches below my shoulders), I initially saw an improvement, but now it's back to separating/drying out quickly.
I'm very low-maintenance when it comes to my hair, but here are some quick stats about my hair/my "hair regimen". I wash my hair once or twice a week and use leave-in conditioner, and about once or twice a month I use shampoo (Burt's Bees, no sulfates); I rarely use a blow-dryer (set on cool), and I prefer to let it air dry. I sleep with my hair in a bun on the top of my head, and I wear it down regularly. I really have no idea what to do to stop my hair from sectioning off the way it does. Should I use less leave-in to keep it from getting weighed down? Should I get a good deep conditioning treatment? I really don't want to lose any more length, but should I have my hair professionally cut? I really appreciate any advice/info you guys could give me, it would be a huge relief to find a solution to my hair woes. Sorry for the monster post!!
(The pic below is my hair on a good day - the day after washing - but it doesn't last very long before the sectioning begins).