Filevault Doesn't Ask for a Password

I've looked around for an answer to this, with no luck.

When I try to set up Filevault, it doesn't give me the option to set up a password. There's no password button, just the button to turn on Filevault. When I do this, it goes through the whole encryption process & gives me a key - just no password. Then, when I restart, there's no requirement that I enter anything. It's like the disk was never encrypted.

Am I missing something here? It feels like I should be prompted to enter a password at some point, & that when I login there should be a prompt for a password or key. Some key step is missing.

Any help would me much appreciated!

 

That makes sense. It wasn't asking for a password because I already have one. I guess I expected something like TrueCrypt, where there's a separate boot password, apart from the regular login password. My education continues. Thanks!