Where's the Ammonia?

Hello,

I set up my new 50-gallon bow-front 2 weeks ago. 8 days ago, I bought
2 Flame dwarf gouramis to begin the cycle. As far as I can tell, they
have been happy, eating, active, and making bubble nests all over for
the past week.

The water seems clear. (I added Bio-Spira after the fish had been in
the tank for 2 days or so - it was the first chance I had to actually
find it in stock at the LFS.)

I've tested the water EVERY day for gH, kH, pH. The pH inched up
slightly - gradually - from 7.0 to 7.2. Otherwise, no changes. Water
is fairly soft for both kH and gH.

Water tested EVERY day for Ammonia, Nitrite, and Nitrate. All 0-0-0,
every darn time. (I confess I got compulsive and started testing for
the "Big 3" twice a day! Ahhh!) I even bought a different testing kit
to make sure I had a good one. Both are in agreement.

So, why aren't I cycling? Where's the ammonia that I am supposed to see
in a new tank? Is it possible that the 2 dwarf Gouramis aren't
producing enough ammonia to be detected in a 50-gallon? I am afraid
that maybe I don't have any good bacteria, or perhaps they are starving
through having little ammonia to eat.

Should I go ahead and add more fish, or should I wait? Should I do a
partial water change/gravel vacuum, or just leave it sit awhile? (I am
planning to do a 20% change/vacuum routine every week for this tank, so
I'd like to get into the tank maintenance routine as soon as I can.
But I don't want to mess up any growing bacteria!)

I was really expecting to see SOMETHING happen before now, so it seems
very strange. I guess all is well, but I wish I had some ammonia to
detect, so that I knew things were progressing. Any thoughts?
Thanks,

- Lisa