Can you have a yeast infection without usual symptoms (pain, redness, itching)? just much much more (whitish, milky) discharge?

Unlikely: As you seem to know, the main symptoms of yeast are irritation, itching, and redness. When there is discharge, usually it is scant and clumpy. "Witish, milky" vaginal fluid could be normal. However, any new, abnormal, or unexplained vaginal discharge should be medically evaluated. Many possible causes, including infections (STDs, bacterial vaginosis), hormonal changes, and more. See your doctor.