im new to guniepigs and have a few questions

Question
I brought my guniepig the other day and the owner told me she could be pregnant, my guniepig is between the ages of 6 - 9 weeks old,i have also noticed that she is bigger and rounder than when i brought her 4 days ago, how can i tell is she is pregnant? also do guniepigs pur like cats? as when i stroke mine on my lap she makes a puring sound.

Answer
they do yes, place a female near a male and hear him purr like theres no tommorow it is a pretty normal sound. the best way to tell is her shape, pregnant guinea pigs become distinctly pear shaped carrying the weight lower down in contrast with a fat pig which will get fat all over with a centrally round belly. feed her alfalfa hay during and after the pregnancy, its rich and full of good stuff for rearing mothers.