Aww bless you!! It sounds like you have got yourself into a bit of a negative mindset about them and the dread of them is making them taste a lot worse than they do! I feel the same about vanilla. Blegh. So anyway, have u ever done chocolate slim fast?? Cuz for me, I whizz up a chocolate shake with less water than your meant to use, with 3 ice cubes and whizz until it's really frothy. And it tastes like a yummier, more chocolatey slim fast. And it's bloomin lovely!! Also I mixed half a choc with half a vanilla also whizzed up with a hand blender and ice and a straw... YUM!!! Make sure u use really cold water and mix it really well cuz I can't stand the powdery taste you sometimes get and now only use the shaker for when I'm out!! If u use a straw you can drink it into the back of your mouth and u won't taste it as much????
Hope it gets better for you hun, perhaps just adjusting how u make them may make a difference xx