may I add...after you wash the playsand squeeze out as much water as possible so that it is only moist (do not let it dry). The idea is to mimic natural soil which will hold a tunnel without collapsing. You can test this by sticking your finger in the moist sans to see if it holds the tunnel.
As for determining whether she is just fat, you will likely see or at least be able to feel (gently) the eggs which are like oval marbles. Whether they are fertile or not is a whole other thing - check with the breeder on their history.
Can you post a few pics of her?
lele
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Chameleon Help & Resource Info
1.0 Nosy Be Panther Chameleon - Cyrus
0.1 Veiled Chameleon - Luna. She's now hanging from her big jungle gym in the sky
1.0 Beardie - Darwin
1.1.1 Side-blotched lizards - Ana and Stan
0.2 felines - Kyndra and Lita
0.1 African Clawed Frog - Skippy
0.1 Chilean Rose Hair Tarantula - Rosa Leigh, Died 4/21/06 
0.1 Goliath Bird-Eater Tarantula - Natasha, donated to science 4/4/06
?.? Pinktoe Tarantula - no name yet