For insanity avoidance digi meters are best 😂
That's good though that you're pH'ing, and good that the problem seems to be correcting itself!
It might be deficiency as you were suspecting, maybe Nitrogen and/or Calcium and/or Magnesium.
Whenever my plants start looking like that I dose them with those three things and it usually does the trick ;)
You could still dose them with a veg feed for the first week or two of flowering to bump up the deficiencies and then switch to flowering feed. Many flowering feeds don't call for feeding until 2-3 weeks anyway.
You got this 💪