Just looking for advice

So my daughter, 9 Weeks old, sleeps between 4-5 SOLID hours a night. She then will wake up and I can sometimes get her to go back to sleep and sometimes shes not having it and I feed her. I keep all lights off, very little interaction...and she usually falls back to sleep BUT from that point on..she only sleeps 30-40 minutes. Then she fusses and wakes up. How can I get her to stop waking up every 30-40 minutes after her feeding? Or is this totally normal and hopefully someday she'll grow out of it? Thanks!!