ADVICE PLEASE!!!!!

Which is more "Accurate", bbt or opk???

I've been tracking my bbt for the past few months even the couple months my Man was out of town! And it seems to show when I ovulate at a normal time! But I tried opk's for the 1st time this month cuz bbt only shows u "After" u ovulate, n I need to know b4! Well my first Positive(and I'm 100% sure it's positive as I even posted on glow and every1 said it's positive) was on CD11 which was also the first day I started taking opk's then I got all negatives starting to next day all the way thru CD15! Until CD16 cane I got another positive and then another on CD17, CD18, CD19, and even on CD20!!! What is going on??? I had my bbt spike .4° on CD19 and .5° more on CD20 and stayed same on CD21 (which is today)! Oh and today, CD2, I finally got a Negative opk test!

My Main question is, When would I have actually ovulated? Since I had 5days of positives? Everything I read says u ovulate 12-48hrs.(average being 24-36hrs.) After LH surge is detected. But they also say that the surge only lasts 1-3days on average so those statistics dont really help me with my situation! Also says that bbt spike occurs "after" ovulation! So why would I continue to have positive opk's for 2days after spike??? Anything u Ladies know would be greatly appreciated I'm very confused about this! So again since I wrote so much it could b a bit confusing, my questions are...

What causes 5days of positives? And most important: When is it likely I actually ovulated??? Cuz the opk's stayed positive for 2days after bbt Spike?!??