“很“ if added into the sentence will mean "Am I very pretty?" usually it will sound like you're are doubting others comoliments. There is no need to add "很“ in this context as you are just asking if you're pretty.
Someone could comment on that! I think 很 is not used here because it's a question! Unless you wanted to ask "am I very beautiful" emphasising your preconceived idea of being already "some" beautiful! Is that right?
Tones, especially the fourth, may change when in the middle of a sentence. Check the notes/tips at the start of each lesson for some rules for using.
tl;dr you heard right, it is ALSO correctly pronounced.
Only if you want to say someone is "very pretty/beautiful." 很 isn't entirely necessary. If you're telling someone they're pretty, it's just a nicer way of saying it, though it's fairly colloquial to just always say it