2.5 weeks into flower and her leaves are yellowing...

Sorry brother just saw this today. Your question must have gotten pushed back especially if there was a lot of people asking questions. Who ever told you it was a potassium issue guessed wrong. If it was potassium the edges of the blades would be browning and the leaves would start to curl and become brittle by now. Looks more like a zinc deficiency issue possibly a boron deficiency or both. Pretty unusual. Its typically due to having a ph above 6.5. Another possibility is an excess of phosphorus can cause this type of lockout also. Your in a state of "nutrient lock" this is why your buds aren't bulking up. I would give her a light flush with 2-2.5 gallons of ph correct water in the 5.9-6.3 range. Add nutes back into the last quart or half gallon. Check the ph of the runoff the first time you run water through her this will give you a better idea if the ph of the soil is higher or lower than what your putting in. Also if you have a TDS meter see what the ppm is of the runoff. It wouldn't surprise me if it was pretty high. Let her dry out a bit more than usual after your flush. Hope this will get her back on track you still have enough time for those buds to fill in. I'll follow your grow. Good luck.