"Too much yeast" won't cause bad flavours in your wine, since the
yeast goes forth and multiplies as soon as it's in the must. By the
time the primary fermentation is over, there is a heck of a lot more
yeast than what you started with.

I would agree, what does it taste like? Meads can be low acid so
adding lemon juice might make it more flavorful. If you describe your
ingredient list in detail it might help.

Joe