I haven't come across many spell tomes, for example, the strongest spell tomes I could find for destruction was Ice Storm, Chain Lighting, and Fireball. What's up with that? I can only find four conjuration tomes, summn Flame Atronach, Raise weak undead, raise stronger undead, and summon familiar. Is this some kind of bug or is there really not that many spells?

there are over 200 spells in the game, they come from places other than tomes dude.

Haven't found any other spells, also dragon shouts don't count. What else would they come in? Or one time use scrolls.