Any idea what her length is from nose to tip of tail? I doubt she's 3 mo old but since some pet stores don't use UVB or not good ones, that can affect their growth rate. Also, they don't tend to feed them enough protein to keep them smaller.
I'm not sure what type of thermostat you're using. Do you think you'd be able to find a picture in google images or post a link so we can see exactly what you mean? Temps are extremely important so want to make sure that you're getting good readings.
A baby should have a basking temp of 110 (but no higher). Most of us use a thermometer with a long wire & probe end to get the basking reading, you place the probe right on the basking log or rock and wait 45 min to an hr for the temp to stop rising before getting the final reading. Then you place the probe end way over on the bottom of the cool side and again wait the required time to get a reading there. Sounds like you have a stick-on round gauge (dial) on the cool side, those are very inaccurate and can be off as much as 20 degrees or more. An infrared temperature gun is also an accurate way to measure temps by holding the gun 2" from the area you're checking.
Unfortunately, the Repti-GLO UVB's have caused all sorts of health issues and if a beardie doesn't like the light or it makes them uncomfortable, they will avoid basking. They can cause serious eye issues and even damage to their eyes, lethargy, loss of appetite, avoiding basking to get away from it which can cause problems digesting which in turn can cause impaction. I looked at the picture that you posted showing the similar way you have yours. I highly suspect your beardie is avoiding it as it shines right directly in her eyes which is NOT good and there is no way to avoid it so she is hiding instead. A fluorescent UVB should be mounted overhead instead and the bright white basking bulb helps prevent any eye damage when the UVB is behind the basking bulb. Those 2 bulbs need to be right alongside each other.
I suggest you replace the UVB with the Repti-SUN 10.0 fluorescent tube as soon as you can and also mount it from above instead. That way, your beardie can also get the benefit of both bulbs at the same time. The distance of the Repti-Sun UVB tube to your beardie while in the basking spot, should be 6 to 8".
Since a good UVB and calcium work together to help synthesize the right amount of calcium in their bodies, make sure you dust with calcium with D3 for 5 days a wk but only 1 feeding a day and with vitamins the other 2 days a wk but only 1 feeding a day.
Would be a good idea to make sure your baby is kept well
hydrated by giving a
bath at least every other day because if a baby gets dehydrated, they can go downhill VERY quickly. A 15 to 20 min
bath is very beneficial.
It's also important to not use a loose substrate, non-adhesive shelf liner, reptile carpet, slate tiles, or paper towels are all safe things to use on the bottom of a baby beardies tank.
Hope this helps, if you have any questions, please let us know.