Hi ladies - I am new to using OPKs and would love your help

I had a positive OPK on Monday cd 13

Yesterday - day 14 I got a -ve OPK (The line was there but not as dark as control)

So is that normal - not to get more that one +ve OPK???

Does that mean the Lutenising Hormone has reached a peak and goes down after you get a +ve OPK??
Should I have even wasted another test after getting a +ve OPK on cd13??

My temps are still low so I am wondering if anyone can tell me what to make of
my chart and my temps & my OPKs?? From all of this I dont think Ovulation has
happened yet - what do you think??

Thanks have a great day
Anna