Blood in stool/ possible milk protein allergy

My LO is almost 14 wks. She has had issues with feeding since she was a couple wks old. Mainly just fussy with eating. No diarrhea and she doesn't spit up much. She is formula fed.. we have tried reflux meds and different formulas.. she is still pretty much the same. She has had some issue with slow growth. Saw the GI doctor, he wasn't concerned but wanted to do a test on her stool to make sure she didn't have blood.

Well I got the call this am that her stool was positive for blood. ( note.. we have never seen blood in her diapers). They suspect a milk protein allergy. I have an appt in 2 days to talk about changing to a special formula.

I'm quite upset.. and on top of it today is my first day back to work.

Anyone else have a baby with this diagnosis? How are they doing? Any tips?

I feel like such a bad mom😥