I agree with Track's idea to an extent - from a role-playing perspective, you may benefit from "delegating" some of your powers to work thematically as if "the bunny did it" - without actually changing their mechanics. For example, your witch may mechanically spend her action on casting a touch spell, but thematically she is doting on her cute familiar or even rebuking him for being naughty.
At any rate, there are some things you can use in the RAW:
1. Replace the almiraj's feat Weapon Finesse with some useful
Since the familiar rules state:
Use the familiar's Dexterity or Strength modifier, whichever is
greater, to calculate the familiar's melee attack bonus with natural
it'll effectively already have Weapon Finesse from that. Relevant familiar feats include: Spell Sponge, Critical Conduit and Familiar Focus (note that any familiar feat requires GM approval).
2. Some useful hexes:
- Beast of Ill-Omen first to behold the bunny after activation suffers the effects of Bane.
- Cursed Wound This can be a way to have your bunny's attacks more horrifying - as they won't heal.
- Peacebond Prevent a target from drawing a weapon ("don't hurt my cute bunny!")"
- Evil Eye Weaken the bunny's target.
- Fortune Use this in conjunction with your bunny's attacks or combat maneuvers.
- Blight Not so useful in combat but cute thematically ("no peeing on that tree bunny!").
- Feral Speech Another one very relevant thematically, but no combat oriented.
- Healing Same here, as well as useful in keeping bunny (and your team-mates) alive.
3. Consider taking a patron who's spells can augment your familiar: Agility, Elements, or Strength for example. Alternatively, Take Peace and use Sanctuary to keep your witch from harm (or abuse it by casting it on the bunny...)
4. Consider taking the Beast-bonded Alternate Class Feature - it allows you to take feats for your familiar instead of the witch, and has some interesting features in higher levels - This will open up all sorts of combat feat chains you can apply on your bunny.
Goodluck - I'd like to see your build when done.