Overstocked, or am I? and what to do

Now, my original plan of stocking was in line with an aquarium book I own, Exotic Tropical Fishes, a thick (and thus presumably authoritative) volume, in which a stocking rule different than the one inch rule is offered. Basically it is the surface area rule with a twist, with the presumption being that bigger fish consume more oxygen than smaller. According to this book, for a ten gallon tank like mine, with a surface area of 200 square inches, something on the order of 16 2 inch fish could be kept, i m below that. Originally I had started the tank out, (in October-I had not read about cyling when I bought the original fish) with 2 dwarf gouramis and 6 neons. Luckily, I had already had the tank up and running before that with plants and snails, and cycling must have already have progressed somewhat, because I did not lose a fish in the initial stages. Unfortuantley i did not know that males (both were male) gouramis are territorial, and this I believe led to both deaths, def. to one, which was harrassed. After the deaths, with all 6neons left, I bought 5 silvertip tetras and 2 otos. According to the book, this combination of fish should work. According to various posts on here, it seems like I m in trouble. I m going to step up water changes to possibly every 4 days.
Basically that was a long winded way of asking if this surface area rule could work, and if not, am I that far off, and if so, what to do? (bring fish back may not be an option. Thanks
Unrelated, but there doesnt appear to be too much algae in the tank, although it is heavily planted (lots of snails), i ve followed peoples advice and fed boiled zucchini and raw spinach, but the otos havent really gotten for it, and they're looking a little thin. Any tips?