Ovulation vs implantation insight please!

Kim • 27/vet tech/ married 8-18-13. Lost our daughter 6-7-16 at 41 weeks
I am day 16 in my cycle, I stopped my BC pills 19 days ago for the first time in 8 years or so.
I've BD'd pretty consistently in this time.
Trying to figure out if what I'm feeling is ovulation or implantation.
Been using opk and had faint lines the past few days (negative before) but very faint/barely anything seen today.
Today I had a very sharp pain in left pelvic area that didn't last long. Never  felt anything like this. Felt it once again later in the afternoon now just a dull pang. Also my nipples have become extremely sensitive to where they semi hurt. I have never had this as an issue before.
I have been following another tracking app that had originally put my fertile week as 5/23-5/28 (as has glow) but as I had been tracking things it said it had moved the fertile week up by 3 days.
Does this sound like ovulation or implantation ? Sorry so long just trying to figure out if I should consistently continue the BD if ovu 😖