You are describing my menstrual cycles to a tea! I can so relate to feeling like AF is coming, to no avail. It has now been 8weeks since my last period (I'm definately not pregnant). Over the years I have had very irregular cycles & as you describe, different each month. Some months I get bad symptoms, other months nothing at all. I'm pretty sure that goes hand in hand with irregular cycles.

I have never been on the pill, so my situation is a bit different I guess. I did have a few years where my cycles were quite regular & I was able to easily conceive (between the ages of 27 until recent, I'm 33 now).

Have you ever charted? Maybe join Fertility Friend & do a few cycles of checking your cervical position & mucus, plus taking your temps. I did this for months before we were actively TTC & found it amazing to learn about my cycles. It will give you a really good insight as to what goes on. You may find that you just haven't been DTD at O time.

It certainly would be worth seeing a GP & get some blood tests done to check out your hormones, particularly if you would like to conceive in the near future.