The poor performance on real CH 12 is not a big surprise because the Mohu Leaf is primary a UHF only design. Real channels 13 and lower are VHF. As a result, the Mohu Leaf would not be an ideal option in your area.
However, your report indicates that reception should be relatively easy if the construction materials used in your home do not included those that reflect, block or absorb TV signals. There are some homes that simply block, reflect or absorb too much signal to be able to achieve acceptable indoor reception. Are you willing to consider mounting an antenna outdoors?
Before spending more on another antenna, you can test reception outdoors, using the existing antenna... You would likely need a factory assembled cable and a 'barrel' connector. Both items are commonly stocked in the big home improvement stores.
Example:
http://www.homedepot.com/p/CE-TECH-5...0-ft/203717795
http://www.homedepot.com/p/PerfectVi...0008/204583259