Hi there! Have you measured feeding and runoff with EC or TDS meter? I don’t think she had nute burn. Probably you misread the symptoms. Leaf tips discolouration is not always the sign of overfeeding. It can be a sign of Ca or K deficiency. Nute burn doesn’t cause yellowing of the older leaves. Young leaves will likely be first to suffer from that. Nitrogen toxicity would not cause yellow fan leaves. But overall underfeeding surely would. In my opinion you simply don’t follow the proper NPK ratio. Giving separate doses of Nitrogen and PK is just weird also.
You need to make a proper solution for bloom phase following feeding chart of your nutrients manufacturer. Then you need to water your plant with mid-strength solution, just about 500 ppm (EC 1.0), water the plant VERY SLOWLY till 10-20 % runoff, and measure runoff ppm. If you have something like 1000 ppm runoff that’s surely overfeeding. Also check pH. Raising pH means likely underfeeding, pH drop may be caused by salt build up. If runoff ppm is the same as your solution, you may raise feeding ppm a little bit. If it’s lower than inflow, the plant is definitely hungry.
Your issue is caused mostly by wrong and unstable NPK ratio I guess.
+2 strains
