I am a clockwork girl - 28 days for the last 25 years, and periods returned within 2 months of having DSs and were right back on track straight off. We are TTC right now and have been for a few months and two months ago on day 21 I had some spotting and crampy pain which I thought may be implantation bleeding which I had with DS1. Then on about day 29 I had pretty heavy bleeding and for a day or two longer than normal. This month, my period has appeared on day 21. what does this mean - could i have been v briefly pregnant last month but it didn't take and now my hormones are taking a while to recover? Or am I just getting old and things are changing because of that 
Any ideas out there v gratefully received....