Sounds more like a nursing strike than self-weaning. Like a PP said it rarely happens before a year. Babies at that age start getting real distracted and since they are mobile they have a hard time sitting still for their meals at the breast. Increase your pumping sessions and there are other things like offering your breast more often, take a nursing vacation together, take baths together, etc. that will hopefully end the nursing strike.
http://www.kellymom.com/bf/concerns/baby/back-to-breast.html
A nursing vacation is usually you and baby hanging out all day with as much skin-to-skin as possible and little to no distractions. It works best if you go topless and the baby is in nothing but a diaper. You aim for you both to be relaxed as possible and that way you can offer the breast and if she refuses you act like it is okay.
You can get through this and still make it to your goal of one year. You're doing great so far. I applaud you for not wanting to give formula since it can no way compare to breast milk. If she doesn't get back on the breast you might be able to get donor breast milk which is still many times better for your daughter than formula.
http://milkshare.birthingforlife.com/