3 week old baby, Diarrhea? Breastfed & No idea(FTM)

3 weeks old..

She gets breast milk thru the bottle every day, strictly breastmilk. Everyday I try to put her to the breast at least 2 times a day to practice her latch & today she did really good so I only bottle fed her two times, and breastfed the other times. She latched really well and stayed on for a good amount of time. I'm not sure if this is diarrhea or regular breastfed babies poop. Should I worry? Any advice on what to watch for? Is my breast milk hurting her tummy? She also has Down syndrome so can this be a reason too? Thanks and sorry for so many questions