I did a ton of side content (basically all of it) so I probably was overpowered then in terms of levels/weapons/Pictos for the main story?

The balance of the game is all over the place, that much I agree on. Especially the final act, which is a mess quite frankly. If you do any side content at all the final boss is a complete joke you probably kill in one shot and miss a bunch of cool attacks and mid-fight cinematics.