So the battery isn't even a year old. Nope, it shouldn't be so low so quickly, but it is possible. Drain the battery completely by leaving your iBook unplugged and wait until it shuts itself off when the battery goes completely dead. Then, plug the iBook in, and hit Shift+Control+Option & and the Power Button (be sure not to hit the fn key in the process). Wait 5 seconds - then hit the power button again to turn the unit on. Let it charge up fully to 100% and then see if you have your hours back if you unplug it.
MacBook Pro (15-inch, Mid 2012) 2.3 GHz Core i7, 16GB, 256GB M4 SSD
iPhone 8 - 64GB S/G • Sound System Audio Engine A2 • Display UltraSharp U2412M 24"
Custom Built Gaming PC Kaby Lake Edition | 16GB DDR4 | GTX 1070 8G