Same thing happened to me about 6 months before we started TTC again, however I had been on the mini pill for a while after DS was born, after being a regular 28 day girl I suddenly became a 21, 23, 26, 24 etc cycler. Also had terrible skin. However as you know we conceived via IVF (male fertility issues) so I cant say whether it impacted things from my side. However I had a 28 day cycle the month of us using IVF and obviously got pregnant.

When I asked my Fert Specialist about it before we started cycling, she sent me off for a scan and I actually had a cyst (which resolved itself the following cycle) - could possibly be something as simple as that

Good Luck babe xx