Pensive Glance

[Julius]

Hi Julius, one of the fun challenges of writing a sonnet is working within that framework and not caving to what is easy in meter and rhyme and making it the best poem it could possibly be. So for me, even suggestions that don't suit the form can be considered in hopes of improving content.

But for me, I don't see a clear volta, a turn from one view to another. What an I missing?

I think the volta is there, but subtle. Up to the couplet the poem is in the present day and about "You". In the couplet thoughts turn to the past and those thoughts are those of "I".
That was the idea, but perhaps it is not definite enough?

Perhaps something more like:-
I feel my age and how years slid away
Yet in your face a trace of yesterday

Because you've mentioned age in the opening lines it seemed more like bookends to me.

And someone once told me that if the volta's left until the couplet it needs to be really strong, a real kicker. I've grown to agree.  

Honestly, to your Narrator that aging face is full of all the passion she started with, I don't get how the couplet sees only a trace. I think if you dig deeper you could come up with something better.

I just know you are right
I always find the couplet the hardest part of a sonnet. When I do my edit I'll see what I can come up with. I must admit that I have, on occasion, abandoned the couplet and finished with a final four line stanza and thus turned the whole thing into a four stanza poem. It is especially tempting when the first 12 lines would neatly break into stanzas (as in this case).
I'll give it some thought and see what transpires. Hopefully it will still end up being a sonnet.