Should I trust cbfm or ovulation spotting? (first cycle using cbfm)

[MeanMrsMustard]

Hi.
I started using cbfm this month. I got 5 days of high, followed by my peak on cd 18.

The thing that's confusing me is I get ovulation spotting quite regularly on or around cd 14. This cycle it was on cd15.
I've looked into ov spotting, and it's thought it is either caused by the egg breaking through, or the start of LH surge. So going by this I either ovulated on cd15 itself, or maybe 16. Yet cbfm says these were only high days, at least 3 days before ovulation.

So, which do you think i should trust? I know cbfm can be inaccurate by missing peak completely, but does it ever "detect" it after it has happened?

Thanks!

Any ideas?

My understanding of how CBFM works is that it says 'high' as soon as it first detects oestrogen above a certain level, and then says 'peak' when it detects the LH surge. If it misses the LH it just continues to say "high" for twenty sticks at vast and pointless expense even though you've ovulated and oestrogen has dropped. The only time it's said 'peak' for me other than at ovulation was it missed ov one cycle and then detected HCG as I was pregnant!
My understanding is that pre-ovulation spotting can happen as several follicles grow rapidly, or as one bursts, so it could be happening a few days before you ovulate.
I found using it that I ovulated later than I had thought based on CM, on day 17 rather than 14.
I think I'd hedge my bets and DTD regularly for that whole period!

Thanks for replying.
Sorry for being dim, but is the follicle bursting not the point when the egg is released?
And also, why happens if my LH surge happens in the afternoon? My first peak reading would be over 12 after surge happens wouldn't it?

The stuff I read implied that you can get some spotting in the days leading up to ovulation, presumably from several follicles expanding and stretching (I had a midcycle scan - it was odd seeing all those follicles getting big I had several that were about 15mm), only one will grow to full size of 2cm and release an egg.
If surge happens in the afternoon and is detected the next morning then you may have already ovulated, but it can be 12-48 hrs after the LH surge. Thats why you should DTD on the "high" days leading up to ovulation as well, so the swimmers are already there waiting for the egg to be released. On subsequent cycles you can use what happened this cycle to predict when you are going to get your peak.
I wouldn't rely on any one thing - if your body signs are telling you that you are about to ovulate then go for it, but I'd keep DTD until the CBFM says low again.
Have you seen the sperm meets egg plan? It suggests every other day from day 8 of your cycle (the week the egg follicles are maturing, until you get a positive on an OPK or peak on your CBFM, then for 3 consecutive days.

Thanks for taking the time to write that. Very helpful. I'll look at that link when im home from work.