Question about Tennessee's castle doctrine and carrying in a vehicle without a permit.

In light of recent events and the country becoming less and less safe for the average citizen I have a few questions about Tennessee's castle laws and age restrictions and how they work together. Last year, as I'm sure TN residents know, a law went into effect allowing non-permit holders to lawfully possess a loaded firearm inside there vehicle. My first question is, "as a 19 year old, does this castle doctrine apply to me?" Am I allowed to have a handgun on my person and in my vehicle even if I am not 21? Everything I've read said that anyone over the age of 18 in TN is allowed to possess a handgun that you only have to be 21 to buy it and the ammo. However, I haven't seen any links to the direct wording of the bill so I remain skeptical. Second, is the firearm able to be kept concealed in the vehicle without a permit under the extension of castle laws?I realise that I cannot have the handgun out of my car for any reason if a do not have a permit. I also know that I have to be 21 to get the permit. I'm just asking about how the castle doctrine applies to people under 21 and without a permit. The big all encompassing question is, "Can I keep a loaded handgun legally in my car at 19 years old in the state of Tennessee?" Links to the laws and other references would be greatly appreciated. via /r/CCW http://ift.tt/28PAKXb