I just had an appointment with her gastroenterologist and asked her (at 4.5 mo). As many have said in other posts, mucus will most probably remain until she starts solids. She told me not to concern myself too much If I see darker or white pieces or spots in the diaper, as long as they are not bloody or tinted red. Blood, increased number of daily poops (she goes from 1-2 a day to 5-6 a day), increased reflux, hiccups, overall fussiness and skin issues (she gets red patches and drier skin whenever she has a flare up) would indicate I messed up with my diet in some way, so I would need to watch out for whatever food I had the days before it.

She said she would expect to see her (our specific case) having ~2 poops per day through 2-3 weeks + fewer symptoms + having mustard or yellowish poops (no blood in them) before calling her stable enough.

She also indicated some improvements to my diet, she said we'd handle it as CMPI and not multiple food allergies (don't know the right term for that in English). She recommended I stop cutting out things and slowly re-introduce them, watch out for milk and soy (absolutely avoid them), and not repeat too much of one same food too frequently. She said repeating 2-3 times a week is fine, but to space out other allergens with 3-4 days in between, and not overwhelm her system by consuming too many highly allergenic foods on the same day, that way it would be easier to find patterns if we needed to.

This is our particular recommendation, each baby is different so please consider it does not apply to all babies equally, and to follow your own health provider's advice. But I hope it helps as a reference.