I'm a bit wary of FF, despite the high recommendations. I'd listen to what your body is telling you!!! Maybe even get a few more bd'ing sessions in if you can, 'specially if you're only CD15, then you could DEF be o'ing NOW!!! It is possible to have fertile cm after o tho, just to confuse the £$%* outta us all!
Chin up, hon, you've still got a chance! Have some
