Well, I think the first step is determining what exactly is causing your hair to break off so you can stop doing it. It sounds like the buns may be causing Breakage in the middle of your head. That could be from the hair drying out in the middle of from the buns being too tight. You may want to switch to a less tight hairstyle for a while that allows your hair to breathe while it grows out. Options could be wash and goes, twistouts/braidouts, a single braid or two going straight back, etc.
If your hair is mushy or stretchy, I would start with a protein treatment. If it's dry and snapping off, I would do a mouisturizing deep conditioner. If your hair is somewhere in the middle, a mostly moisturizing deep conditioner that contains some kind of protein may help.
You should get into a schedule of deep conditioning regularly, like at least once a week. It doesn't have to be a tedious process either. Just use a deep conditioner on your hair in the shower after shampoo rather than regular conditioner. Allow it to sit while you bathe/shower and rinse before you get out.
As far as keeping the breakage under bay, you also want to ensure that the tools you use to detangle or style aren't contributing to your hair breaking off. Whether you choose to finger detangle, use a wide tooth comb, or a paddle brush, make sure it actually works well with your hair type.
To get your hair back on track as fast as possible, I would also lay off of using heating tools or if you do, be sure to use heat protectant.
Keep your hair moisturized so it doesn't break off. There are different ways to do this- frequent washes/cowashes, frequent application of leave in conditioner and sealing with oil, etc. Use whatever method works for you, but do it consistently. Don't ever allow your hair to get dry to the point it's ready to break or snap off.
Trim your hair every few months to get rid of any damage.