If I do have a massive phosphorous deficiency shou...

Its like in autumn the leaves are colouring, The chlorophyll turns away( consumed by the plant) and the regular colour appears a mix of orange and yello, and later its brown and the leaves dies. Your plant comes to the end of his lifecircle and thats how it looks like. kepp the track you ar going, she will be ready soon (10-14 days)

Are you sure you have a P deficiency? The symptoms of phosphorous deficiency are dark / metallic blue patches on lower leaves. On the other hand potassium (K) deficiency looks like uneven yellowing with rust spots on lower leaves. Is that what you see on the lower leaves? Cause I can't spot that on the pictures; what I see is purpling leaves due senescence or autumn color effect. The former happens when the plant is close to its end, the later is a technique that removes nitrogen from the feed in mid flowering, forcing the plant to use its stores, when done right, it results in yellow / red / purple leaves that looks like plants during autumn. Autos usually takes between 8 to 10 weeks so I believe that what you are seeing is a plant that's close to harvest and so its consuming its reserves.

yes you do have Phosphorous and Potassium deficiencies, but that doesnt mean you should harvest now. You can check the trichomes to see if the plant is ready, using a 40x minimum magnifier , cloudy or white means THC is present, clear means not ready yet and amber means you'll have more of a couch lock effect. otherwise you can check the pistills to see if you're ready, you're looking for something like 70/80% brown pistils. So no you're not ready to harvest, and you should probably add some PK and chelation agent for a week maybe two before a two week flush... sorry for the bad news, but it's the truth ! hope this helps ! 🚀