How much Bitcoin did I mine in December 2013? I just realized I had a bitcoin mining program installed back in November/December 2013. 

I am trying to figure out if it's worth going through all my backups to see if I can still find the wallet file.

I assume that based on the duration, the date and my MacBook Pro specs, I should be able to get a rough estimate on how much I had mined. Maybe someone can help me figure out, what the difficulty was back then, and based on the MacBook Pro specs, how much I could have mined.

Starting date: 25. November
Ending date: 22 December

Hardware: MacBook Pro (Mid 2012) - 2.5 GHz (3210M) Intel Core i5 Ivy Bridge -  Nvidia GeForce GT 650M with 512 MB 

I had my MacBook on pretty much 24/7.

I am just looking for a rough estimate.
You can go to https://en.bitcoin.it/wiki/Non-specialized_hardware_comparison for a table of mining performance of many different CPUs and GPUs.  The GT650M is reported as doing 17.8 Mhash/s; let's round it up to 20.  There is a range of values for various Core i5 CPUs from 5 to 20 Mhash/s; let's be generous and call it 20 also.  So you were mining at a combined rate of say 40 Mhash/s; in scientific notation that's 4.0e7 hash per second.  You mined for 28 days which is 2.4e6 seconds, so you performed a total of 9.6e13 hashes.

Next we need to know the mining difficulty around that time.  There is a chart at Blockchain.info.  It was increasing rapidly during that time but in early December it was around 707,000,000, or 7.1e8.  Each 1 unit of difficulty corresponds to 2^32 = 4.3e9 hashes needed to mine one block.  So at that time, it took about 3.0e18 hashes to mine one block.

As such, you would expect to have mined 9.6e13 / 3.0e18 = 3.2e-5 blocks.  The block reward at that time was 25 BTC per block (see https://en.bitcoin.it/wiki/Controlled_supply) and so you would have earned, on average,  BTC 8e-4, or in other words BTC 0.0008.

At today's exchange rate of USD 6149 per bitcoin, that is worth just under USD 5.00.

This is of course an average, or expected value.  If you were mining for a pool, this may or may not have been enough to actually earn a payout.  If you were solo mining, you would have had to mine a full block worth BTC 25; the probability that you did so is about 3.2e-5.