Ah, the subjunctive... What a tricky modality it is! :)
You have grasped the meaning of the sentence perfectly: The speaker is indeed saying that it is nearly two o' clock and they still haven't arrived at their destination.
Now, the να+subjunctive structure infuses the speaker's attitude into this statement. The indicative is about (statement of) facts, but the subjunctive is about feelings. While "ακόμα δεν φτάσαμε" would simply state a fact, "ακόμα να φτάσουμε" reveals how the speaker feels about the fact that they haven't arrived at the uncle's house yet. The way I read it, the speaker is saying (i.e. implying) something along the lines of: It is late and I am tired of being on the road for so long. I am frustrated that it is taking us so long to get to my uncle's house.
Just getting the ball rolling here. I'm sure you'll be getting more insights into this. For now, HTH. :)