Good you're giving her the right stuff. You may not need the pk because the canna a and b is well balanced, you want a ratio around 3-2-2, N still dominate. Big plants re-vegging outdoors eat a lot, she needs a lot of N as well.
Your 25 gallon bag is probably fine, you mentioned that she might be rootbound already. I always stick my plants in the ground, if I have room, because a plant in the ground will always get bigger than one in a container. The downside is being stuck, not able to move the plant around. Even if your soil sucks you can fill your hole with goodies and make sure it drains well.
A 'naturally' grown cannabis plant in the ground outside develops a massive root system, only about a foot deep but 3-6 feet in all directions, basically a carpet of roots. There's just no way a container can replace the space they need. As container growers we make up for that by using rich mixes and feeding much heavier than you would almost any other plant. I've seen re-vegged plants the size of yours get massive when stuck in a hole. Just something to think about, she'll do fine if you leave her in the 25 gal.
At some point I think you're going to need to prune the hell out of her. Re-vegged plants outdoors always produce way, way too many new shoots. I can see it happening already on yours. You'll probably do better waiting a week or two until the re-veg is fully under way but you'll probably need to remove 1/3 of the tops plus a bunch of leaf. You want to direct the new growth into 15-30 main tops. I'm not a big pruner, I don't like leafing unless I have to but sometimes it's necessary.
20 years ago or so a buddy of mine had a plant he called the 'crystal sativa'. It was the best of strains, the parent stock was a purple type with fairly wide leaves. For some reason this particular seeding didn't turn purple and had extremely thin leaves. It produced like crazy and was one of the frostiest plants I've seen. It was always bushy, always wanted to produce lots of tops like a rasta's dreadlocks.
It was the most naturally re-veggable plant I've ever seen. He revegged it indoors a couple times and gave it to me to reveg. I stuck it in a 10 gallon pot, revegged it under a 1000 watt light and it got massive. I removed dozens of tops, leafed it several times, still ended up with 30-40 main colas, huge yield, best smoke ever.
I harvested her indoors in May and gave the frame back to my friend . He stuck it in a huge hole he dug in his back yard. By the time it revegged for the last time it had over a 100 tops, he had to remove half of them plus piles of leaves.
He had to keep it under 6 feet tall so the neighbors couldn't see it. He hung bricks off it to tie it down. It would lift the bricks and still get too tall. It was 6 foot, 10 feet around, weirdest ganja bush you've ever seen, extremely thin sativa leaves, dozens of tops, with all these bricks tied to the branches hanging down. If his neighbors saw it they probably thought he was nuts. He got a few lbs, it was amazing. Your plant could surprise you.
