Flute player here - I've been playing for over 25 years - yikes! - has it been that long? I'm in a local community concert band and I've " giged" with choir groups.
Remember the old " pop ' bottles - even a water bottle will work - try directing the air by changing your lip formation: across and down into the bottle. The air flow goes over the mouth piece -direction of the air goes down toward your chin not out like you would blow up a balloon. It's all in the lip formation - not like whistling- in fact - I've been playing so long I REALLY cannot whistle - honest!
Try with just the mouth piece alone.
Yes, you get dizzy at first - but as they say practice , practice. Breath support is like any instrument- deep lung support - AND, we haven't even started getting the tongue working to articulate the air movement.
Let me know how it goes.

Hope this helps.
Good Luck,
Cheryl