Nitro use will fall off at about week 6 anyways ..... since branching and stretch is over.
Most bloom Nutes have a lower nitro to supplement. The fade will continue over time.
The flowers are looking more for P and K for weight and flowering. The next 3 weeks are the bulking weeks . As she finishes “ later “ you can ween the feed with water only a week before chop , to stymie the excess storage of overfeed.
As stated ... any big box hardware store will have good nute supplements for the flowering stage.
Tomato Tone , Dr. Earth Flower Girl ( recommend ) , even as simple as grabbing a bag of FFOF and topdress a bit THEN water in.
Really that simple ...... the topdress “ recharges “ the medium with everything she wants.
My go to method instead of synth bottles.