Flute help-what could be wrong with it?

I would go to a repair shop and ask to try out some plugs for the holes just in case. I know when I switched from closed hole to open hole flute, I could swear I was fully covering the keys and it wasn't so. So my first suggestion is to get the plugs and play with it for about a week, if it keeps doing what it's doing, you may have pads out of line. One of your springs may not be working either, but that would be easier to tell because the key wouldn't come back up. It won't cost anything to get it looked at in a shop, they can tell you what's wrong without charging anything.