That's right, you have to fertilize the plants! I use Seachem Flourish Comprehensive. It's all micronutrients, but the plants can get Nitrogen, Phosphate, and Potassium from your tap water.
Don't worry about the ammonia - the plants are the essential part. A little won't hurt the plants any, in fact it's a nutrient for plants. Actually, you want to get the nitrite out of there, so don't put in any ammonia - this will force the plants to eat up the nitrites and when they hit zero, time for fish.
Plants consuming ammonia is a separate system than bacteria converting from one molecule to another to another. They co-exist in your tank. Plants also filter toxin's from the water. Get involved with the plants - the nitrifying bacteria will develop at the usual cycle rate