So, my Ped wants me to try an elemental formula for a few days to see if my LO "takes to it" a little better than she has to my BM. I've been on a strict MSPI diet (I read every label, there's no chance I've been ingesting dairy or soy unless the food labels are lying). But she also said my LO may not take it, since she's only ever had BM.

She doesn't want me to transition slowly (like half breastmilk, half formula) because she wants to "figure this out" by this Saturday. I'm torn....I also want to figure out my LOs issues, and I'm not philosophically opposed to formula at this point (I feel like I can safely say I gave BFing and pumping more-than-fair shot), but I'm worried about constipation, my LO not liking the taste, and in short---making her feeding problems worse.

Have any of you successfully switched from exclusive BM to an elemental formula at 4 months or beyond?