Help T3i so slow focusing, keep missing shots

Hello, I am a beginner with a canon T3i.  I got the camera last year so I could get good pictures of my first newborn Granddaughter,  but now that she just turned one and is moving around a lot more than a newborn,  the camera takes so long to focus that I keep missing good shots because it's so slow.  I shoot mostly indoors but even with good light it's still so slow, I keep missing good shots.  I read a lot of reviews before buying this camera which took me a long time to save up for, so I know it's a great camera. It's so frustrating!  I mostly shoot in Auto or P, I have a Canon EFS 18-135mm 1:3.5-5.6 IS lens and a Canon EF 50mm 1:1.8.  Please help any advice would be much appreciated.

MM