Just because you've not had sore BBs before AF before doesn't mean you wont ever get this as a pre AF symptom. Over the years what I get has changed. I went years without getting sore BB's but for about the last year I've been getting that as a pre AF symptom. I also used to get really heavy AF's and haven't for the last few years - our bodies can change from time to time. I didn't used to get PMS but now I do. That said, at CD20 you wouldn't have implanted (if you are pregnant) so of course your level would have been normal then. Unfortunately you are going to have to wait and see, and make sure you test with FMU when you do!!!