There is no need to stop a small amount of parsley unless it is in any way preventing her from eating more hay. Hay is the most important part of her diet right now.
You need to write a food diary and also take note of her behaviour for a few weeks to find a pattern and maybe a cause of the problem. Your vet can also check the diet in detail to help you figure it out x
It could be the parsley and you may need to cut it out or cut down on the amount you're introducing. Otherwise, I will ask if she is shedding? Because that can often cause smaller poops for a time. I strongly agree with keeping a food and behaviour/poop diary, mine was extremely helpful when Bandit went through a stasis issue and really helped to see when he was beginning to improve etc.
I will start the diary today its kind of hard to document her poop though with peers in there. So far I've introduced pellets over an 8 day period and parsley over a 3 day period. I've now started green leaf lettuce.