Baby constipation??

My baby girl Is 2.5 weeks old and only had one bowel movement in the last 24 hours. She is breast and formula fed. Probably heavier on formula than breast milk because my supply is low. Is it OK for to only have one bowel movement in 24 hours? She's been fussy and not wanting to sleep tonight and I figured it was her belly hurting. She doesn't have a fever or anything. Should I be concerned or call the pediatrician?