little bit of advice please

Hi everyone, we have been trying to concieve for a while now and every month af turns up i am normally pretty regular maybe sometimes one or two days early or late but that it. This month i should have been ovulating around 6th-12th september in this time i had loads of clear stringy discharge which is what i always get when ovulating but then on the 18th september it started to happen again so when did i ovulate?? So confused. I was due af on 28th september i am.now 11 days late but if i ovulated the week later i am only 3 days late iv done a hpt came back bfn but i am feeling very very sick sometimes its only their for a while but it can last all day or night i feel different to every other month i have been urinating alot more, headaches and feeling quite hungry surely i cant be imagining all this??