Less milk intake

My baby is 5 months old. I noticed that she drinks less milk now. The last time she used to drink 2-3 hrs 100-120 mls but now she can go stretch to 4 hrs with just 50 mls milk. I noticed she is losing weight too. No more buns shape on the hands or legs :( But besides that she is well. She is active, growing with the right milestones and she is even sleep more now. Any other mothers face the same thing? Or should i bring her to see the doctor? Btw she is on mixed feeding. Recently i even changed her milk powder brand. #firsttimemom #firstmom #worriedmom