Hey Andi,
I just finished my smock and I made several adjustments to make it smaller. I am super short and have tiny shoulders, so I almost always have to alter patterns.
Here's what I did:
1. I shortened the pattern
above the darts:

So I cut the pattern straight across and lifted it about an inch (you'll need to measure on yourself to see exactly how much).
Like so:

2. I made it smaller all around by cutting about 1/2 inch off at the fold line of the pattern. You'll need to smooth out the neckline when you're done cutting, but it's no biggie. Again, the amount you take in will be different for you. My bust measurement is 34" and taking off two inches was just right for me (1/2" off of the pattern).
3. I shaved off the shoulders a bit, but only at the very top. I don't have a picture because I did this after I had constructed the smock and tried it on. I only took off a little bit, but it made a big difference!
I did not take anything off the bottom because I didn't need to after the alterations at the bust line. If the pattern fits you there, just shorten it at the bottom.

GL! Just remember to keep trying it on, especially before you cut ("try" on the pattern).