I didnt know either, but I had a great gp before I moved. He told me lots of women may have 2 or 3 anovulatory cycles every 20 or so cycles and this is completely normal. The balance of hormones is very delicate and plenty of things can disrupt this and cause you to prepare to ov but not actually pop, iyswim.
FSH is Follicle Stimulating Hormone. It is released by your pituitary gland and prompts a follicle in your ovary (or more than one) to mature and produce an egg. Estradiol (I think) is the hormone released by the follicle once it is mature enough to actually release an egg, and the rise in Estradiol prompts the body to release LH (Lutenising Hormone), which causes the actual release. Contraband ov sticks detect this LH surge just before ovulation actually occurs.
In an anovulatory cycle, you may see FSH released (prepping a follicle), but no Estradiol, and/or no LH, meaning your body begins to attempt to ovulate but does not actually pop the follicle open. OR, if you have pcos, you could have high levels of LH all the time but no FSH or Estradiol (which is why ov sticks don't work for pcos sufferers - it looks like you are about to ov all the time but you never do).
It's really easy to disrupt this - stress is well known for making the witch turn up late, and this is because cortisol (stress hormone) in the body inhibits FSH, so delays ovulation and so delays ertd. Likewise, weight loss can stimulate ovulation as you store estrogen and estradiol in your fat cells, and as those fat cells are burst open and the fat released and metabolised by the body, you experience an estradiol surge. I swear that is how I conceived DS; I lost 11lb in 2 weeks and ov'd for the first time in 144 days, and bam. Made a baby.
Charting temps gives you a picture over time (often a few months) of your cycles. When you release Estradiol and LH, your basal body temperature (the internal temperature of the body at rest after at least 3 hours sleep) goes up by just under a degree, as these hormones create energy in the body and heat. You get a basic digi thermometer and a chart (fertility friend or Taking Charge Of Your Fertility by Toni Weschler have good ones), and in the morning, at exactly the same time (set an alarm), before you move or get up or do anything at all, you take your temperature and record it on the chart. Once you've ov'd, your temp goes up. You can tell you ov'd as your temp stays up for three days in a row. The next bit (the 2ww!) is called your Luteal Phase, and here you are either duffed (temp stays high sixteen days or more) or your temp drops down again and the witch appears. The Toni Weschler book explains it in more detail. Charting was how I knew to test for DS as my temp had been up 18 days and I was all 
it's not instant and it can take a few months to see a pattern, but if you see temps going up at the same point, plus Ewcm, you can be fairly sure you are ovulating. If you have an anovulatory cycle, you will get the witch with no temp rise. Oh, and word of advice: sleeping with your mouth open can affect your temp as you are taking measurements of 0.10 of a degree, so take your temp in your fanjo or bum for more accurate results, and always take it the same way as internal temps seem higher, and you are looking for quite a small change.
Sorry for the essay! hope all that makes sense? I have done a lot of reading on this because of the pcos so I have it in laymans terms. I found charting really useful and interesting, and it does make you feel less powerless and more in tune with your body. The book is often available in the library and I just photocopied the relevant pages at work and a whole bunch of the charts.
How are you feeling now? You could also google about using high strength evening primrose oil to help you ov. I did for 2 months before conceiving Ds but that could be a coincidence.
Hope all that helps! Have finger ache now from iPad typing!