Feats like Empower and Heighten spell I know how to "activate" them but how do I know they are working because it seems to me that they aren't I am a Level 3 sorcerer

Both Empower and Heighten Spell are only good once you gain a few levels. Level 3 sorcerers can only cast 0 and 1st-level spells. Empower Spell requires a sorcerer to expend a spell slot two levels higher than the spell actual's level, so you can't currently use it (you'd need to be at least level 4 and even then, can only use it on 0-level spells, which is not worth it). Heighten Spell increases your spell's level (in your case, you can only increase 0-level spells to 1st level spells), which make them harder to resist if the opponent gets a save. So it will be useless on spells that don't allow for a save (like Acid Splash), but useful on spells that do (like Daze).