My experience with AF & pg is this (I have PCOS).....

Usually my cycles were 35 days sometimes more, it actually shortened when I lost weight (low GI diet) and exercised regularly. No spotting during my cycle at all. When AF showed it started as brown blood first day then red blood for approx. 3-5 days. I occassionally had dull O type pains, no EWCM. But given I only fell pg three times (without IVF) I highly doubt it was ovulation and also I had blood tests to check for ovulation with both tests coming back negative, so my cycles were often 'annovulatory' (ie no ovulation). When I have fallen pg, I have taken FMU (first morning urine, midstream) tests and they have shown positive lines (ie: pregnant) approx. 1 week after AF should be due (ie: at 42 days). All my m/c's occured in the first trimester with spotting type red blood then heavy bleeding pretty much straight away.