sleeo through the night

my girl has been steadily sleeping through the night since 4 months plus. recently at 8 months plus, she has been waking up one time at between 3-5am for milk. we tried to increase milk intake per feed but she is not consistently finishing it so we did not permanently increase the milk. she is also taking breakfast cereals and porridge for lunch. not sure is this period of growth spurt or sleep regression? we don't know what's wrong