The amount you're feeding for veg sounds fine, or you can increase if you want. I would agree that you could probably up the pellets since you have a pretty big rabbit there, but that will also depend on a few factors.
Though there are general recommended feeding amounts for pellets with pet rabbits, the metabolism of each individual rabbit will vary regardless of weight. So you can have two rabbits of the same weight that might need to be fed a different amount of pellets.
I generally gauge the amount of pellets to feed based on a few conditions (with their grass hay always being free fed/unlimited). Less pellets if they aren't eating a pile of hay the size of their body per day, have small dark fecal poop, mushy cecotropes, or dental issues, but are maintaining good body condition/weight. And less pellets if they're overweight. I may feed more pellets if they aren't maintaining a healthy body condition/weight, if they're eating more hay per day than a pile the size of their body, or act like they are constantly starving. But only if they don't have any poop issues.
I would be cautious about switching pellets so suddenly(for future reference), even if it's just for a day. Rabbits have a delicate balance of microflora in their digestive tract, and sudden food changes can upset this balance, often resulting in digestive problems, sometimes very serious ones. The exception to this is grass hay. It rarely causes issues when introduced into the diet suddenly(good quality hay and not spoiled).
Usually pellet changes are recommended to be made gradually and over at least 2 weeks time. If you run out of pellets, it's often better to let the rabbit continue being free fed just hay(provided they are eating the hay really well). I would rather do a day without pellets and lots of hay, then risk digestive upset by the sudden change of pellets.