Sorry to hear you are worrying. I saw your post on the extended bfing board and came to offer you my own experience, for what it's worth. I have been bfing since Meg was born. She still nurses five to six times in 24 hours and night-nurses.
AF returned when Meg was nine months old, and I had painful periods just as I did pre-Meg (I have endometriosis). Bummer. I didn't pay attention to ovulation signs for months afterward, but slowly my cycles evened out and now they are much more predictable, and the cramping is lighter. O is really clear for me, to the day--I have mittelschmerz and cramping for a few days afterward every time. My lp is short, too, maybe a day shorter than it was pre-Meg, but always the same.
It sounds as though you usually know your ovulation day, but this time was hard to tell? Why don't you keep some ovulation predictor kits in your medicine chest for your next cycle, just in case it's not so clear again? Sometimes it's worth knowing what's going on, just for your own piece of mind. If your lps really are only 5 days long, that might be something to take to a gyn. If they're 11, well, that might be a problem...and it might not. I got pregnant with 12 day lps and a little hcg to up the progesterone.
As to treatments for it, a daily vitamin B complex (you only need one, but they all work together, so it's better to have them all) might help you, as might some daily Flax oil or evening primrose oil and cutting out or lessening caffeine, sugar, and simple carbs. Just some suggestions.
I hope things are better for you soon, and that your body is ready for baby-making come next Thanksgiving or so.
Keep us posted.
Kam, mamamama! to 2-year-old Meg