[CarleyGee]

I think you should listen to your hairdresser.
For now, before you dye it lighter, I would try making your hair healthy from vitamins and such, so that when you do dye it, it will turn out better.
Excessive dying can cause it to fall out/break/ or severly damage it, like you said.
It wouldn't really matter if you dye it back to your natural cause just because
change the color, that doesn't change the texture and such.

You might want to get a second opinion from another hairdresser about the condition of your hair, just in case so you're not missing out on the blonde ^_^