I know it can be very confusing! Romaine is definitely safe to feed daily. Of course more variety is considered better, but depending on where you live that may not be practical or possible. I aim to feed three types of veggies per day and I rotate them when I can, but I usually have a type of lettuce as one of them (sometimes romaine, sometimes red leaf, etc). In the winter they get less variety, in the summer they get more. The main “formula” that I follow is a lettuce, an herb, and dark leafy green. So could be romaine, cilantro/coriander, and kale. Or romaine, oregano (in the summer when I grow it), and swiss chard. Or red leaf, basil, and carrot tops. You get the idea! In the winter they often get mostly romaine and kale, since that’s whats available and of decent quality at my supermarket. Growing your own herbs or spring mix is also an economical way to incorporate more variety. Lettuce is very easy to grow inside if you have a sunny window or a plant light. 🙂

If you are feeding a high quality pellet and your bun eats his hay, veggies are really more of a source of enrichment than a dietary necessity. Some people’s buns don’t do well on pellets and in those cases it’s much more important to feed a high variety of veggies. Peppers I would consider more of a treat, so I wouldn’t feed too much of them, but a small amount each day is fine. 🙂

If she is only 4 months old she should have a source of alfalfa in her diet. Most people prefer to feed a junior rabbit pellet with alfalfa, rather than having alfalfa hay, because it can be harder to transition to grass hay when a bun has been getting only alfalfa. But, you can give adult pellets and some alfalfa hay instead. At her age she can have almost unlimited pellets, which means you can give a generous amount and then refill the bowl once it’s empty. Some people do this for the first year, others only till about 6-8 months, depending on the size of the bun (larger rabbits take longer to grow). From what you described she may need more pellets. If you switch her to a different pellet just be sure to do it gradually (there are usually instructions on the package on how to do this).

You also want to introduce new greens very slowly to make sure they don’t upset her gut.

Were her normal poops soft, or did she just have extra cecals? It’s pretty normal for young rabbits to have extra cecals because the diet is more rich.

And yes it would be ok to just provide some alfalfa along side her timothy, and give a bit extra pellets. I would also weigh her regularly and feel along her spine and hip bones to make sure she doesn’t feel too boney.