Deflated Keg

Maybe it's nothing.

Maybe it's something.

But whatever it is, after spending the time to transfer my Saa-Wheat! beer to a keg, I come to the kegerator and my CO2 tank is out.

OUT.

There's not a drop left of gas in the tank. Sure, I suppose it's been a little while since I've filled that tank. But I don't feel like it should quite be time for a fill yet. I've force carbonated a number of beers off of it too. I can't help but feel it's a leak though. It could just be my past experiences with CO2 leaks in my kegerator manifesting itself in some obscure paranoia. I think it's time to replace my home made manifold with a real one. I think it's also time to get something that will work a little better than Teflon tape at sealing these threads. I'm not quite sure what that substitute would be yet. I'd really appreciate some recommendations.

I feel like my beer is so vulnerable now... All... Uncarbonated...