This is an old comment, but anyone else seeking help with this, maybe try this. This is going to sound weird, but pretend you are a cat hissing, do it now. Now, as you are doing it, close your mouth ever so slightely into a size of maybe "blowing air". Now soften the hiss into a soft blow where it feels like it comes off the roof of your mouth like the hissing sound did, and say the word. See if this helps.