I remember being in your position, reading all the conflicting information about rabbit diet when we first got our two. I came to the conclusion that most of the diets you read about are probably OK, as long as you don't suddenly change the diet. An all pellet and timothy diet is certainly very easy for you, and healthy for the animal.
I will describe what we do, because it is somewhat unusual. Most would consider it too time consuming, but it works well for us, since we have a large vegetable garden and some fruit trees, and because I know a lot about wild plants and animals, and feel comfortable doing things that others might not do.
First, ours always have access to plenty of timothy. In the morning they get a salad of mostly leafy greens, which usually includes any or all of these: romaine lettuce, mixed baby greens, kale, collards, swiss chard, and various herbs, such as basil, parsley, dill, or cilantro. I don't subscribe to the notion that these are unnaturally rich, because all of our food plants were bred from wild plants, and are nutritionally similar to their wild relatives, which wild rabbits eat. In the afternoon, they get a couple of scoops of a timothy based pellet, a large hand full of oat hay, and a large handful of alfalfa hay.
The rest of their diet varies seasonally, much like that of wild rabbits:
Winter: I bring them prunings (branches and twigs) from our fruit trees and shrubs, which include apple and pear, and a bit of blueberry. I prune my trees little by little, all winter long, so the rabbits can have a little every day (most people prune their fruit trees all at once to get it out of the way). I also bring them a few twigs of wild tree species, like sugar maple, beech, oak, hawthorn, serviceberry, and ash....just to keep things interesting. An invasive shrub they love is autumn olive. They love the twigs and bark in winter, and nibble on the young leaves in spring. I began feeding them this when I saw how much the wild cottontail rabbits like it.
Spring, summer, fall: During this period, our rabbits "free range" with our chickens in a 1/3 acre fenced in yard, which has fruit trees, shrubs, grasses, and weeds. No chemicals are used on anything grown in our yard. The rabbits eat whatever they want out there, which includes many different weeds and grasses, apple twigs and leaves if they can reach them, and, in late summer and fall, the fallen apples.
I know some people would say this is too rich, etc. etc...But the key is that they eat a very wide variety of foods, and changes come on gradually with the seasons. It's not like they go from eating no fresh grass to gorging on it. Green plants appear gradually throughout the growing season, so it is like introducing a food gradually into the diet. The apples would be controversial, but I noticed that they never eat a lot at once, probably because they have so many other options. They just nibble on them. I think if you had your rabbit on a pellet only diet, then suddenly started throwing in large quantities of apple, he would have intestinal problems. This apparently does not happen when the apples appear gradually with change of season, and when the rabbit has many other food options.
Basically I noticed that this is pretty similar to how wild rabbits eat: lots of woody stuff in winter, gradually changing to fresh greens and grasses in spring and summer, adding whatever wild or farm-stolen fruits they can get in late summer and fall. Wild rabbits don't seem to be dropping dead from this, so I figured it was OK for my rabbits. And I think our buns really love the variety. Most animals would take variety over monotony if given a choice. Makes for a more interesting life.
I realize you are probably not going to follow a regimen anything like this, but I think it illustrates some of the basic ideas, both controversial and accepted, in pet rabbit diet.
Good luck!
