hmmm just having a squiz, it *could* still be O spotting... is there is a possibility that you O'd on CD 15 (makes it hard to gauge with the cold playing havoc with your temps ) and that *could* be Ovulation spotting from when the egg popped (can take days for it to 'come down' and can last quite a few days. BUT from my experience it is really light spotting (kinda like if you nick yourself shaving etc)...is this heavier than that?

my experience with implant spotting is that it lasted a good four days and was not bright red, but i did need a panty-liner/light days pad...HTH!

also another cool tip i learnt from FF when i was having issues locating an O date was to switch to 'research' mode. it takes into consideration alot more 'clues' that the company has found a pattern with but are still trialling before using it in the 'advanced' mode... for example, on my successful cycle, FF gave me NO ovulation detected on advanced, so i switched to 'research' and sure enough it corresponded with when i thought i had ovulated...just a thought!

goodluck with it all and i have everything that you get that gorgeous BFP in no time!