I've been told your cervix feels a bit like the tip of a nose, but with a small indentation (the opening)... if you can feel it easily it's considered low, you judge the texture being firm, medium or soft and if the indentation is easily discernible then that's considered open - so if you have low, soft and open that's the most fertile stage and the time of ovulation... but this is all what I've read in theory, I haven't actually put it into practice other than the odd wee curious poke around up there!