So I have learned when I ovulate based on a painful one-sided feeling, just like you, but I only started trusting that pinching feeling after 3-4 cycles of temping, seeing that my temp always rose the day after the strong pinch.
My friend, however, had a different experience. She was seeing an RE and had PCOS, so she would get frequent ultrasounds throughout her cycle to look at follicle maturity etc. She said that very frequently during her TTC journey, she would get a strong one-sided pinch. Certain she had ovulated, she'd go in for an ultrasound and bloodwork, and they would tell her that she hadn't ovulated yet, even though she was very close on the side she had the strong pinch. So she feels that ovulation pain is very unreliable.
My experience was different, and yours may well be too, but just wanted to introduce the possibility that you might be just 1 day ahead or so, just because that line is pretty dark for 7 DPO!