Are there also brown circles on the shady side of the fruit, or just on the sun-facing areas?

To me that looks like sunburn, because the brown circles are exactly facing the sun. It was a tough, tough, brutal 5 weeks here in So Cal for plants starting the 2nd week of August.

Citrus trees can take 5-7 years to get really established, especially little 'Meyer'. 2 or three, its still getting itself going. Your baby tree got some sun/heat stress.

Also looks like it needs some Nitrogen, but now is NOT a good time because the Citrus Leaf Miner will be around a while longer. Citrus trees like a lot of Nitrogen.

Also keep watch for the Huanglongbing disease, though it doesn't look like what you have.

The other thing, I saw whitefly on my 'Meyer' yesterday, so check the leaf undersides and keep them washed off for the next couple of months.

Here is a link that might be useful: Huanglongbing Citrus alert

I agree with hoovb - I think your Meyer got cooked. Meyers actually do just fine with partial sun, BTW. The UV index in CA is so high, I have one that lives in bright shade and is 10' wide by 8' tall.

Thank you for your helpful replies!

Smiles,
Sooz