Are you in coco yoda? That is the only reason I can see you would be watering at 6.1
If you watered at 6.1 and your runoff was 5.3 that puts your soil around 4.5! Wrap your mind around it for a second, if you are watering high and the runoff is coming out low then the water is actually raising the runoff some so your actual soil ph is way too low. The fact that your meter is off the charts on tds probably means, yes, your soil is saturated with excess nutes and acidifying the soil pretty bad. Actually, the plant looks better than what I would have thought considering those readings. She must be a fighter!
So look, to get a rough calculation of your soil ph here is what I do. If your water is 6.1 and runoff is 5.3 then that is -.8 difference. So 5.3 - .8= 4.5 A way to check that you are correct is then take that number, 4.5 and add it to what your water was 6.1 and divide by 2. That should be your soil ph. So 4.5 + 6.1 = 10.6 / 2 = 5.3
That is very rough but it gets you in the ballpark without doing a slurry test which is one of the only true ways to know what your soil ph is.
Honestly, I would probably flush the hell outta her and dose back at 1/2 - 3/4 strength and I bet she responds real well with some bud explosions.
Take care