What should I try next?

First time poster here and of course I’m having a issue with my plant. I’m experiencing super slow growth and light green/yellowing leaves up top with a couple bottom leaves dyeing as well. I’ve been battling this issue for over a month and it’s progressively getting worse. I’m overwhelmed with the amount of things it could possibly be and I’m just looking for some direction. I’m on day 63 since planting the seed and it’s a Gorilla Cookies feminized from Expert Seeds. It’s in a 3 gallon fabric pot with canna coco and perlite mixed with 4 tablespoons of 4-4-4 Dr Earth organic dry amendments. Lighting is a 480w mars hydro and it’s currently at 25” above canopy. Tempers range between 70-85F and RH is between 40-65(sometimes it spikes to 70-80% for a couple minutes when I shower). I have a 10” fan for air circulation and a exhaust fan venting to attic. I’v been watering with well water ph’d to between 6.4-6.8 and two tsp cal/mag whenever the top soil gets dry. This isn’t my first grow as I have three plants under my wing and have progressively been getting better but I’m stumped on this one and not ready to switch it to flower till I get this figured out. The only thing that changed from my last grow was the bigger light. I was using 300w viper spectra. I’ve tried playing with the distance but I didn’t notice a change. On 8-7-19 I added 3 tbs of DR. Earth 3-9-4 bloom and mixed it into the surface thinking it was a deficiency and then on 8-7-19 I got impatient and gave it 1 gallon with 10ML of Fox Farm grow big ph’d to 6.41. Still she’s hurting. What should I do?

Here’s a picture.

I can't zoom in to see for sure, but it looks like the newer leaves have scorched tips? Did they happen only after the last couple feedings, or have they been there since the slow growth began?

It happened mostly after the last feeding. Probably just to much N.

10 ml per gallon of grow big is way to much.

With the dry amendments you added they work a lot better if there’s some microbes in the medium to help break them down. Earth worm castings/compost...even recharge or some sort of microbial inoculant to help break the nutrients down and get things moving along.

Plant is looking ALOT better today. Leaves are going green again and the leaves are very very perky today. Not sure if the dry amendments I added are finally starting to work or if is from the brow big I added but she’s happy for now. I’m thinking next watering I’ll just ph to 6.4 with cal/mag and if she stays happy I’ll switch her to flower. I want to say she was hurting for some N?