My limited experience is that rabbit poop does not smell bad. On two occasions I piled some bunny poop on the palm of my hand and had a sniff. I detected an herbal odor with a onion like overtone on the first occasion, the second time there was the herbal odor with a sulfur like overtone. This has satisfied my curiosity and I have not repeated this experiment!
What does smell bad is the cecal pellets, the cecum pellets, that a rabbit produces at least once a day. You can own a rabbit for years and never know they are expelling these things. They are soft and mushy and smell bad since they are full of liver/bile enzymes. The reason you may not know about this is that the rabbits immediately re-ingest them the instant they come out. If you bunny gets too fat or gets spinal arthritis, they won’t be able to reach back to eat them and the pellets will get stuck in the fur around their rectum or fall on the floor where you can step on them with your bare foot. Ugh!
Infected anal glands is a good suggestion.
You said your girl is a few years old. My understanding is that female rabbits have a 90%+ probability of developing uterine cancer by age five. They need to be neutered before reaching 5 years.
About feeding the pellets and hay. Why not give the bun a little more variety such as green leafy vegetables. Also your rabbit will like a treat every day. An apple slice, a banana slice. My rabbits currently like fiji apples and they like their banana slice a little green. Also now they get a few raw whole almonds every day.