Mozzarella can be a very difficult cheese to make. It will turn out like cheese but quite often it will not stretch correctly. Lots of recipes are harder than they need be so here's a great simple recipe that (usually) works.
2 gallons cold milk
3 teaspoons citric acid (this may vary with the milk taking more or less)
Mesophilic starter packet (optional)
dissolve citric acid in warm water and stir into cold milk
Bring milk temp up to 90 degrees
You may add lactic culture to develop flavor (1 packet of Mesophilic starter culture)
stir in 1 teaspoon liquid rennet diluted in 1 cup of water
Let set for 1/2 hour cut into small cubes
stir gently slowly raising temperature to 95
When curds settle to bottom of vat
drain off whey and cover curds with 145 degree water
Stretch curds , form balls and drop in cold water
Let us know how this recipe works for you!