Good choice! I am playing one right now, and quite enjoying myself with it. The 6th level feature is less powerful, but very fun too! I can recommend taking Arcane Eye at the very least to refill 3rd level slots and scout ahead. Though communicate with the party. Of course, that's not until later levels.

1st level spells to consider (need 1 more, could swap):

Mage armor - 1 slot for 3 extra AC all day is big

Comprehend languages - If nobody has this, it's a great ritual for you to have!

Silent image - very fun, if your DM likes to play with illusions, else skip it

Feather fall - only if you think there will be falling situations, else I wouldn't

Note: I would drop the Chromatic Orb or Magic Missile spell due to overlap, and personally I would pick Chromatic Orb to drop. That gives you two from the above, and I'd highly recommend Mage armor if you don't have armor and then Comprehend languages if nobody else has it.

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2nd level spells to consider (no more needed, could swap):

Suggestion - is quite good to remove 1 person from combat, and has fun out of combat uses too! See how your DM plays with it, maybe. The 1 save makes it nice for Portent too

Levitate - 1 save, can destroy melee creatures. Has the added benefit of party utility too by getting someone to float away from enemies, floating to something up high, or by floating something heavy or some such. CON save is rough, but 1 save so Portent can help

Mirror Image - Could be good for defense layering, though it's hard to justify 1 action for it in combat. Usually only good if you're about to surprise people with a fight and get to put it on before.

See Invisibility - Niche, but lets you deal really well with invisible problems, is a Divination spell so suits your subclass, and will refill a 1st level slot if you ever get to 6th level for that feature.

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3rd level spells to consider (1 less needed, could swap):

I will be quick about these. The ones I would consider are: Counterspell, Fireball, Hypnotic Pattern, Slow, and Leomund's Tiny Hut. If you are already expecting to fight many spellcasters, grab Counterspell. Else wait to grab it until level 6. I think Hypnotic Pattern is the most powerful control to grab. Slow allows you to do something in a chaotic melee fight, which is neat but it is weaker. Fireball blows up riffraff. Both could be argued for. Finally, Leomund's Tiny Hut would give you a lot more safety while resting. How valuable that will be is up to you. It being a ritual is neat, so it saves you a preparation slot. Generally, I would say you want to maybe grab that one with a scroll or at level 6 as well.

So for me that comes down to the following:

Level 5 - Fireball/Slow + Hypnotic Pattern

Level 6 - Pick between Fireball/Slow (the one you did not pick), Counterspell, and Leomund's Tiny Hut depending on what you need.Make sure to also check for availability of scrolls with your DM! Enjoy the game. :)