I'm so glad you finally got good results. When I make lactic cheese in the winter, I place my pot of cultured milk in a sink of warm water to give it a bit of a boost, as the basement where I make cheese is pretty cool. Also, the curd is pretty delicate and I learned that it is better to not cut the curd, but rather to use a skimmer to gently scoop it out of the kettle and into the cloth-lined colander. That way, the curd doesn't break up so much.
Keep up the adventure!