i've realized pretty quickly that the 1 inch per gal is pretty meaningless. not only can you sometimes have much LESS than that (ie, you wouldn't keep a 12" green terror in a 12 gallon tank!), but a lot of times, you can have considerably more than that!! for instance, look at the stock of my 29 gallon (in my sig).. it's quite a bit more than 29" of adult fish i think, but it's working out really well!
good luck with your tanks. 2 swordtails and 1 gbr doesn't sound like too much to me, though i'm no expert!