Hello.

I have an issue where I picked the Expert Destruction perk & ever since then all my destruction magic has totally went limp. Thunderbolt is more like a static electricity discharge, & incinerate may as well be like throwing lit matches at people. Anyone know wtf has happened? Btw, I am a Vampire & I noticed this during the day but I've tried testing it indoors & at night & it seems the same. Also I am lvl 28.

I don't know if this is due to some sort of strange bug you are experiencing, or if this is just a result of the under powered, ill-balanced nature of Destruction magic inherent in the Vanilla version of Skyrim. If you search the boards you will find massive amounts of debates on the balance of Destruction magic, and hence, you will find many mods aimed at making destruction magic a bit more powerful.

Solution:
if your game is not bugged, try one of the mods aimed at increasing the power of destruction magic. My personal preference is "Balanced Magic" by I Mystic (not exactly sure of her name).

I do have mods but it was like I choose Expert Destruction & it either reduced the power of my spells or everyone suddenly got stronger.