Blind Familiar trying to deliver a touch spell

Here’s the setup:

  • My familiar is adjacent to a target. My familiar is blinded.

  • I cast a touch spell. My familiar uses its reaction to deliver the spell.

Normally, being blinded causes you to attack at disadvantage, so I attack at disadvantage, right? I’m nearly certain about this, but wanted to confirm.

Background reading:

Casting while blinded in D&D 5e (mentions casting while blind, but not specifically the issue of a familiar delivering a touch spell)

Blinded + casting a spell with a bonus action + Find Familiar

Does an invisible familiar delivering a touch spell have advantage?