When is an invention still "new" and patentable?

Thanks everyone for previous answers, I appreciate the assistance.

I have co-founded a startup based in CA. We develop software and mobile apps, specializing in financial services and consulting businesses.

Regarding patent protection, I know that a patent won't be granted for something that has already been published in a journal etc. and is therefore not "new". Is this always true? In any case, I was wondering what kind of conduct would qualify as making the invention public. For instance, we are a new company and some of our new developments I like to discuss in small circles of experts in the field, who generally keep in touch and provide feedback. I guess the question is, when is something so "public" it would not be patentable anymore?