If you stay on the gas, the bike shouldn't (under normal conditions) nosedive.
I would suggest getting someone to video tape you. Almost all of us feel like we are wide open when the tape later shows us to be nowhere near it.
Blipping the throttle may work for some smaller jumps where you have enough running room beforehand that it doesn't matter that you let off prior, but when you start hitting bigger jumps with less running room, you'll need to be on the gas all the way through the turn and up the jump.
I also get a little nervous making any changes on the jump face, like blipping the throttle, changing gears, switching lines, etc. since it greatly increases the chance of doing something wrong with no time to correct it.